Added comprehensive documentation for TreeView and Layout components, including usage examples, advanced features, and developer references.

.claude/commands/developer.md

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+# Developer Mode
+
+You are now in **Developer Mode** - the standard mode for writing code in the MyFastHtml project.
+
+## Primary Objective
+
+Write production-quality code by:
+
+1. Exploring available options before implementation
+2. Validating approach with user
+3. Implementing only after approval
+4. Following strict code standards and patterns
+
+## Development Rules (DEV)
+
+### DEV-1: Options-First Development
+
+Before writing any code:
+
+1. **Explain available options first** - Present different approaches to solve the problem
+2. **Wait for validation** - Ensure mutual understanding of requirements before implementation
+3. **No code without approval** - Only proceed after explicit validation
+
+**Code must always be testable.**
+
+### DEV-2: Question-Driven Collaboration
+
+**Ask questions to clarify understanding or suggest alternative approaches:**
+
+- Ask questions **one at a time**
+- Wait for complete answer before asking the next question
+- Indicate progress: "Question 1/5" if multiple questions are needed
+- Never assume - always clarify ambiguities
+
+### DEV-3: Communication Standards
+
+**Conversations**: French or English (match user's language)
+**Code, documentation, comments**: English only
+
+### DEV-4: Code Standards
+
+**Follow PEP 8** conventions strictly:
+
+- Variable and function names: `snake_case`
+- Explicit, descriptive naming
+- **No emojis in code**
+
+**Documentation**:
+
+- Use Google or NumPy docstring format
+- Document all public functions and classes
+- Include type hints where applicable
+
+### DEV-5: Dependency Management
+
+**When introducing new dependencies:**
+
+- List all external dependencies explicitly
+- Propose alternatives using Python standard library when possible
+- Explain why each dependency is needed
+
+### DEV-6: Unit Testing with pytest
+
+**Test naming patterns:**
+
+- Passing tests: `test_i_can_xxx` - Tests that should succeed
+- Failing tests: `test_i_cannot_xxx` - Edge cases that should raise errors/exceptions
+
+**Test structure:**
+
+- Use **functions**, not classes (unless inheritance is required)
+- Before writing tests, **list all planned tests with explanations**
+- Wait for validation before implementing tests
+
+**Example:**
+
+```python
+def test_i_can_create_command_with_valid_name():
+  """Test that a command can be created with a valid name."""
+  cmd = Command("valid_name", "description", lambda: None)
+  assert cmd.name == "valid_name"
+
+
+def test_i_cannot_create_command_with_empty_name():
+  """Test that creating a command with empty name raises ValueError."""
+  with pytest.raises(ValueError):
+    Command("", "description", lambda: None)
+```
+
+### DEV-7: File Management
+
+**Always specify the full file path** when adding or modifying files:
+
+```
+✅ Modifying: src/myfasthtml/core/commands.py
+✅ Creating: tests/core/test_new_feature.py
+```
+
+### DEV-8: Command System - HTMX Target-Callback Alignment
+
+**CRITICAL RULE:** When creating or modifying Commands, the callback's return value MUST match the HTMX configuration.
+
+**Two-part requirement:**
+
+1. The HTML structure returned by the callback must correspond to the `target` specified in `.htmx()`
+2. Commands must be bound to FastHTML elements using `mk.mk()` or helper shortcuts
+
+**Important: FastHTML Auto-Rendering**
+
+- Just return self if you can the whole component to be re-rendered if the class has `__ft__()` method
+- FastHTML automatically calls `__ft__()` which returns `render()` for you
+
+**Binding Commands to Elements**
+
+Use the `mk` helper from `myfasthtml.controls.helpers`:
+
+```python
+from myfasthtml.controls.helpers import mk
+
+# Generic binding
+mk.mk(element, cmd)
+
+# Shortcut for buttons
+mk.button("Label", command=cmd)
+
+# Shortcut for icons
+mk.icon(icon_svg, command=cmd)
+
+# Shortcut for clickable labels
+mk.label("Label", command=cmd)
+
+# Shortcut for dialog buttons
+mk.dialog_buttons([("OK", cmd_ok), ("Cancel", cmd_cancel)])
+```
+
+**Examples:**
+
+✅ **Correct - Component with __ft__(), returns self:**
+
+```python
+# In Commands class
+def toggle_node(self, node_id: str):
+  return Command(
+    "ToggleNode",
+    f"Toggle node {node_id}",
+    self._owner._toggle_node,  # Returns self (not self.render()!)
+    node_id
+  ).htmx(target=f"#{self._owner.get_id()}")
+
+
+# In TreeView class
+def _toggle_node(self, node_id: str):
+  """Toggle expand/collapse state of a node."""
+  if node_id in self._state.opened:
+    self._state.opened.remove(node_id)
+  else:
+    self._state.opened.append(node_id)
+  return self  # FastHTML calls __ft__() automatically
+
+
+def __ft__(self):
+  """FastHTML magic method for rendering."""
+  return self.render()
+
+
+# In render method - bind command to element
+def _render_node(self, node_id: str, level: int = 0):
+  toggle = mk.mk(
+    Span("▼" if is_expanded else "▶", cls="mf-treenode-toggle"),
+    command=self.commands.toggle_node(node_id)
+  )
+```
+
+✅ **Correct - Using shortcuts:**
+
+```python
+# Button with command
+button = mk.button("Click me", command=self.commands.do_action())
+
+# Icon with command
+icon = mk.icon(icon_svg, size=20, command=self.commands.toggle())
+
+# Clickable label with command
+label = mk.label("Select", command=self.commands.select())
+```
+
+❌ **Incorrect - Explicitly calling render():**
+
+```python
+def _toggle_node(self, node_id: str):
+  # ...
+  return self.render()  # ❌ Don't do this if you have __ft__()!
+```
+
+❌ **Incorrect - Not binding command to element:**
+
+```python
+# ❌ Command created but not bound to any element
+toggle = Span("▼", cls="toggle")  # No mk.mk()!
+cmd = self.commands.toggle_node(node_id)  # Command exists but not used
+```
+
+**Validation checklist:**
+
+1. What HTML does the callback return (via `__ft__()` if present)?
+2. What is the `target` ID in `.htmx()`?
+3. Do they match?
+4. Is the command bound to an element using `mk.mk()` or shortcuts?
+
+**Common patterns:**
+
+- **Full component re-render**: Callback returns `self` (with `__ft__()`), target is `#{self._id}`
+- **Partial update**: Callback returns specific element, target is that element's ID
+- **Multiple updates**: Use swap OOB with multiple elements returned
+
+### DEV-9: Error Handling Protocol
+
+**When errors occur:**
+
+1. **Explain the problem clearly first**
+2. **Do not propose a fix immediately**
+3. **Wait for validation** that the diagnosis is correct
+4. Only then propose solutions
+
+## Managing Rules
+
+To disable a specific rule, the user can say:
+
+- "Disable DEV-8" (do not apply the HTMX alignment rule)
+- "Enable DEV-8" (re-enable a previously disabled rule)
+
+When a rule is disabled, acknowledge it and adapt behavior accordingly.
+
+## Reference
+
+For detailed architecture and patterns, refer to CLAUDE.md in the project root.
+
+## Other Personas
+
+- Use `/technical-writer` to switch to documentation mode
+- Use `/unit-tester` to switch unit testing mode
+- Use `/reset` to return to default Claude Code mode

.claude/commands/reset.md

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+# Reset to Default Mode
+
+You are now back to **default Claude Code mode**.
+
+Follow the standard Claude Code guidelines without any specific persona or specialized behavior.
+
+Refer to CLAUDE.md for project-specific architecture and patterns.
+
+## Available Personas
+
+You can switch to specialized modes:
+- `/developer` - Full development mode with validation workflow
+- `/technical-writer` - User documentation writing mode

.claude/commands/technical-writer.md

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+# Technical Writer Persona
+
+You are now acting as a **Technical Writer** specialized in user-facing documentation.
+
+## Your Role
+
+Focus on creating and improving **user documentation** for the MyFastHtml library:
+- README sections and examples
+- Usage guides and tutorials
+- Getting started documentation
+- Code examples for end users
+- API usage documentation (not API reference)
+
+## What You Don't Handle
+
+- Docstrings in code (handled by developers)
+- Internal architecture documentation
+- Code comments
+- CLAUDE.md (handled by developers)
+
+## Documentation Principles
+
+**Clarity First:**
+- Write for developers who are new to MyFastHtml
+- Explain the "why" not just the "what"
+- Use concrete, runnable examples
+- Progressive complexity (simple → advanced)
+
+**Structure:**
+- Start with the problem being solved
+- Show minimal working example
+- Explain key concepts
+- Provide variations and advanced usage
+- Link to related documentation
+
+**Examples Must:**
+- Be complete and runnable
+- Include necessary imports
+- Show expected output when relevant
+- Use realistic variable names
+- Follow the project's code standards (PEP 8, snake_case, English)
+
+## Communication Style
+
+**Conversations:** French or English (match user's language)
+**Written documentation:** English only
+
+## Workflow
+
+1. **Ask questions** to understand what needs documentation
+2. **Propose structure** before writing content
+3. **Wait for validation** before proceeding
+4. **Write incrementally** - one section at a time
+5. **Request feedback** after each section
+
+## Style Evolution
+
+The documentation style will improve iteratively based on feedback. Start with clear, simple writing and refine over time.
+
+## Exiting This Persona
+
+To return to normal mode:
+- Use `/developer` to switch to developer mode
+- Use `/reset` to return to default Claude Code mode

.claude/commands/unit-tester.md

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+# Unit Tester Mode
+
+You are now in **Unit Tester Mode** - specialized mode for writing unit tests for existing code in the MyFastHtml project.
+
+## Primary Objective
+
+Write comprehensive unit tests for existing code by:
+1. Analyzing the code to understand its behavior
+2. Identifying test cases (success paths and edge cases)
+3. Proposing test plan for validation
+4. Implementing tests only after approval
+
+## Unit Test Rules (UTR)
+
+### UTR-1: Test Analysis Before Implementation
+
+Before writing any tests:
+1. **Check for existing tests first** - Look for corresponding test file (e.g., `src/foo/bar.py` → `tests/foo/test_bar.py`)
+2. **Analyze the code thoroughly** - Read and understand the implementation
+3. **If tests exist**: Identify what's already covered and what's missing
+4. **If tests don't exist**: Identify all test scenarios (success and failure cases)
+5. **Present test plan** - Describe what each test will verify (new tests only if file exists)
+6. **Wait for validation** - Only proceed after explicit approval
+
+### UTR-2: Test Naming Conventions
+
+- **Passing tests**: `test_i_can_xxx` - Tests that should succeed
+- **Failing tests**: `test_i_cannot_xxx` - Edge cases that should raise errors/exceptions
+
+**Example:**
+```python
+def test_i_can_create_command_with_valid_name():
+    """Test that a command can be created with a valid name."""
+    cmd = Command("valid_name", "description", lambda: None)
+    assert cmd.name == "valid_name"
+
+def test_i_cannot_create_command_with_empty_name():
+    """Test that creating a command with empty name raises ValueError."""
+    with pytest.raises(ValueError):
+        Command("", "description", lambda: None)
+```
+
+### UTR-3: Use Functions, Not Classes (Default)
+
+- Use **functions** for tests by default
+- Only use classes when inheritance or grouping is required (see UTR-10)
+- Before writing tests, **list all planned tests with explanations**
+- Wait for validation before implementing tests
+
+### UTR-4: Do NOT Test Python Built-ins
+
+**Do NOT test Python's built-in functionality.**
+
+❌ **Bad example - Testing Python list behavior:**
+```python
+def test_i_can_add_child_to_node(self):
+    """Test that we can add a child ID to the children list."""
+    parent_node = TreeNode(label="Parent", type="folder")
+    child_id = "child_123"
+
+    parent_node.children.append(child_id)  # Just testing list.append()
+
+    assert child_id in parent_node.children  # Just testing list membership
+```
+
+This test validates that Python's `list.append()` works correctly, which is not our responsibility.
+
+✅ **Good example - Testing business logic:**
+```python
+def test_i_can_add_child_node(self, root_instance):
+    """Test adding a child node to a parent."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)  # Testing OUR method
+
+    assert child.id in tree_view._state.items  # Verify state updated
+    assert child.id in parent.children  # Verify relationship established
+    assert child.parent == parent.id  # Verify bidirectional link
+```
+
+This test validates the `add_node()` method's logic: state management, relationship creation, bidirectional linking.
+
+**Other examples of what NOT to test:**
+- Setting/getting attributes: `obj.value = 5; assert obj.value == 5`
+- Dictionary operations: `d["key"] = "value"; assert "key" in d`
+- String concatenation: `result = "hello" + "world"; assert result == "helloworld"`
+- Type checking: `assert isinstance(obj, MyClass)` (unless type validation is part of your logic)
+
+### UTR-5: Test Business Logic Only
+
+**What TO test:**
+- Your business logic and algorithms
+- Your validation rules
+- Your state transformations
+- Your integration between components
+- Your error handling for invalid inputs
+- Your side effects (database updates, command registration, etc.)
+
+### UTR-6: Test Coverage Requirements
+
+For each code element, consider testing:
+
+**Functions/Methods:**
+- Valid inputs (typical use cases)
+- Edge cases (empty values, None, boundaries)
+- Error conditions (invalid inputs, exceptions)
+- Return values and side effects
+
+**Classes:**
+- Initialization (default values, custom values)
+- State management (attributes, properties)
+- Methods (all public methods)
+- Integration (interactions with other classes)
+
+**Components (Controls):**
+- Creation and initialization
+- State changes
+- Commands and their effects
+- Rendering (if applicable)
+- Edge cases and error conditions
+
+### UTR-7: Ask Questions One at a Time
+
+**Ask questions to clarify understanding:**
+- Ask questions **one at a time**
+- Wait for complete answer before asking the next question
+- Indicate progress: "Question 1/5" if multiple questions are needed
+- Never assume behavior - always verify understanding
+
+### UTR-8: Communication Language
+
+**Conversations**: French or English (match user's language)
+**Code, documentation, comments**: English only
+
+### UTR-9: Code Standards
+
+**Follow PEP 8** conventions strictly:
+- Variable and function names: `snake_case`
+- Explicit, descriptive naming
+- **No emojis in code**
+
+**Documentation**:
+- Use Google or NumPy docstring format
+- Every test should have a clear docstring explaining what it verifies
+- Include type hints where applicable
+
+### UTR-10: Test File Organization
+
+**File paths:**
+- Always specify the full file path when creating test files
+- Mirror source structure: `src/myfasthtml/core/commands.py` → `tests/core/test_commands.py`
+
+**Example:**
+```
+✅ Creating: tests/core/test_new_feature.py
+✅ Modifying: tests/controls/test_treeview.py
+```
+
+**Test organization for Controls:**
+
+Controls are classes with `__ft__()` and `render()` methods. For these components, organize tests into thematic classes:
+
+```python
+class TestControlBehaviour:
+    """Tests for control behavior and logic."""
+
+    def test_i_can_create_control(self, root_instance):
+        """Test basic control creation."""
+        control = MyControl(root_instance)
+        assert control is not None
+
+    def test_i_can_update_state(self, root_instance):
+        """Test state management."""
+        # Test state changes, data updates, etc.
+        pass
+
+class TestControlRender:
+    """Tests for control HTML rendering."""
+
+    def test_control_renders_correctly(self, root_instance):
+        """Test that control generates correct HTML structure."""
+        # Test HTML output, attributes, classes, etc.
+        pass
+
+    def test_control_renders_with_custom_config(self, root_instance):
+        """Test rendering with custom configuration."""
+        # Test different rendering scenarios
+        pass
+```
+
+**Why separate behaviour and render tests:**
+- **Behaviour tests**: Focus on logic, state management, commands, and interactions
+- **Render tests**: Focus on HTML structure, attributes, and visual representation
+- **Clarity**: Makes it clear what aspect of the control is being tested
+- **Maintenance**: Easier to locate and update tests when behaviour or rendering changes
+
+**Note:** This organization applies **only to controls** (components with rendering capabilities). For other classes (core logic, utilities, etc.), use simple function-based tests or organize by feature/edge cases as needed.
+
+### UTR-11: Required Reading for Control Render Tests
+
+**Before writing ANY render tests for Controls, you MUST:**
+
+1. **Read the matcher documentation**: `docs/testing_rendered_components.md`
+2. **Understand the key concepts**:
+   - How `matches()` and `find()` work
+   - When to use predicates (Contains, StartsWith, AnyValue, etc.)
+   - How to test only what matters (not every detail)
+   - How to read error messages with `^^^` markers
+3. **Apply the best practices** detailed below
+
+---
+
+#### **UTR-11.1 : Pattern de test en trois étapes (RÈGLE FONDAMENTALE)**
+
+**Principe :** C'est le pattern par défaut à appliquer pour tous les tests de rendu. Les autres règles sont des compléments à ce pattern.
+
+**Les trois étapes :**
+1. **Extraire l'élément à tester** avec `find_one()` ou `find()` à partir du rendu global
+2. **Définir la structure attendue** avec `expected = ...`
+3. **Comparer** avec `assert matches(element, expected)`
+
+**Pourquoi :** Ce pattern permet des messages d'erreur clairs et sépare la recherche de l'élément de la validation de sa structure.
+
+**Exemple :**
+```python
+# ✅ BON - Pattern en trois étapes
+def test_header_has_two_sides(self, layout):
+    """Test that there is a left and right header section."""
+    # Étape 1 : Extraire l'élément à tester
+    header = find_one(layout.render(), Header(cls=Contains("mf-layout-header")))
+
+    # Étape 2 : Définir la structure attendue
+    expected = Header(
+        Div(id=f"{layout._id}_hl"),
+        Div(id=f"{layout._id}_hr"),
+    )
+
+    # Étape 3 : Comparer
+    assert matches(header, expected)
+
+# ❌ À ÉVITER - Tout imbriqué en une ligne
+def test_header_has_two_sides(self, layout):
+    assert matches(
+        find_one(layout.render(), Header(cls=Contains("mf-layout-header"))),
+        Header(Div(id=f"{layout._id}_hl"), Div(id=f"{layout._id}_hr"))
+    )
+```
+
+**Note :** Cette règle s'applique à presque tous les tests. Les autres règles ci-dessous complètent ce pattern fondamental.
+
+---
+
+#### **COMMENT CHERCHER LES ÉLÉMENTS**
+
+---
+
+#### **UTR-11.2 : Privilégier la recherche par ID**
+
+**Principe :** Toujours chercher un élément par son `id` quand il en a un, plutôt que par classe ou autre attribut.
+
+**Pourquoi :** Plus robuste, plus rapide, et ciblé (un ID est unique).
+
+**Exemple :**
+```python
+# ✅ BON - recherche par ID
+drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+
+# ❌ À ÉVITER - recherche par classe quand un ID existe
+drawer = find_one(layout.render(), Div(cls=Contains("mf-layout-left-drawer")))
+```
+
+---
+
+#### **UTR-11.3 : Utiliser `find_one()` vs `find()` selon le contexte**
+
+**Principe :**
+- `find_one()` : Quand vous cherchez un élément unique et voulez tester sa structure complète
+- `find()` : Quand vous cherchez plusieurs éléments ou voulez compter/vérifier leur présence
+
+**Exemples :**
+```python
+# ✅ BON - find_one pour structure unique
+header = find_one(layout.render(), Header(cls=Contains("mf-layout-header")))
+expected = Header(...)
+assert matches(header, expected)
+
+# ✅ BON - find pour compter
+resizers = find(drawer, Div(cls=Contains("mf-resizer-left")))
+assert len(resizers) == 1, "Left drawer should contain exactly one resizer element"
+```
+
+---
+
+#### **COMMENT SPÉCIFIER LA STRUCTURE ATTENDUE**
+
+---
+
+#### **UTR-11.4 : Toujours utiliser `Contains()` pour les attributs `cls` et `style`**
+
+**Principe :**
+- Pour `cls` : Les classes CSS peuvent être dans n'importe quel ordre. Testez uniquement les classes importantes avec `Contains()`.
+- Pour `style` : Les propriétés CSS peuvent être dans n'importe quel ordre. Testez uniquement les propriétés importantes avec `Contains()`.
+
+**Pourquoi :** Évite les faux négatifs dus à l'ordre des classes/propriétés ou aux espaces.
+
+**Exemples :**
+```python
+# ✅ BON - Contains pour cls (une ou plusieurs classes)
+expected = Div(cls=Contains("mf-layout-drawer"))
+expected = Div(cls=Contains("mf-layout-drawer", "mf-layout-left-drawer"))
+
+# ✅ BON - Contains pour style
+expected = Div(style=Contains("width: 250px"))
+
+# ❌ À ÉVITER - test exact des classes
+expected = Div(cls="mf-layout-drawer mf-layout-left-drawer")
+
+# ❌ À ÉVITER - test exact du style complet
+expected = Div(style="width: 250px; overflow: hidden; display: flex;")
+```
+
+---
+
+#### **UTR-11.5 : Utiliser `TestIcon()` pour tester la présence d'une icône**
+
+**Principe :** Utilisez `TestIcon("icon_name")` pour tester la présence d'une icône SVG dans le rendu.
+
+**Le paramètre `name` :**
+- **Nom exact** : Utilisez le nom exact de l'import (ex: `TestIcon("panel_right_expand20_regular")`) pour valider une icône spécifique
+- **`name=""`** (chaîne vide) : Valide **n'importe quelle icône**. Le test sera passant dès que la structure affichant une icône sera trouvée, peu importe laquelle.
+- **JAMAIS `name="svg"`** : Cela causera des échecs de test
+
+**Exemples :**
+```python
+from myfasthtml.icons.fluent import panel_right_expand20_regular
+
+# ✅ BON - Tester une icône spécifique
+expected = Header(
+    Div(
+        TestIcon("panel_right_expand20_regular"),
+        cls=Contains("flex", "gap-1")
+    )
+)
+
+# ✅ BON - Tester la présence de n'importe quelle icône
+expected = Div(
+    TestIcon(""),  # Accepte n'importe quelle icône
+    cls=Contains("icon-wrapper")
+)
+
+# ❌ À ÉVITER - name="svg"
+expected = Div(TestIcon("svg"))  # ERREUR : causera un échec
+```
+
+---
+
+#### **UTR-11.6 : Utiliser `TestScript()` pour tester les scripts JavaScript**
+
+**Principe :** Utilisez `TestScript(code_fragment)` pour vérifier la présence de code JavaScript. Testez uniquement le fragment important, pas le script complet.
+
+**Exemple :**
+```python
+# ✅ BON - TestScript avec fragment important
+script = find_one(layout.render(), Script())
+expected = TestScript(f"initResizer('{layout._id}');")
+assert matches(script, expected)
+
+# ❌ À ÉVITER - tester tout le contenu du script
+expected = Script("(function() { const id = '...'; initResizer(id); })()")
+```
+
+---
+
+#### **COMMENT DOCUMENTER LES TESTS**
+
+---
+
+#### **UTR-11.7 : Justifier le choix des éléments testés**
+
+**Principe :** Dans la section de documentation du test (après le docstring de description), expliquez **pourquoi chaque élément ou attribut testé a été choisi**. Qu'est-ce qui le rend important pour la fonctionnalité ?
+
+**Ce qui compte :** Pas la formulation exacte ("Why these elements matter" vs "Why this test matters"), mais **l'explication de la pertinence de ce qui est testé**.
+
+**Exemples :**
+```python
+def test_empty_layout_is_rendered(self, layout):
+    """Test that Layout renders with all main structural sections.
+
+    Why these elements matter:
+    - 6 children: Verifies all main sections are rendered (header, drawers, main, footer, script)
+    - _id: Essential for layout identification and resizer initialization
+    - cls="mf-layout": Root CSS class for layout styling
+    """
+    expected = Div(...)
+    assert matches(layout.render(), expected)
+
+def test_left_drawer_is_rendered_when_open(self, layout):
+    """Test that left drawer renders with correct classes when open.
+
+    Why these elements matter:
+    - _id: Required for targeting drawer in HTMX updates
+    - cls Contains "mf-layout-drawer": Base drawer class for styling
+    - cls Contains "mf-layout-left-drawer": Left-specific drawer positioning
+    - style Contains width: Drawer width must be applied for sizing
+    """
+    layout._state.left_drawer_open = True
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+
+    expected = Div(
+        _id=f"{layout._id}_ld",
+        cls=Contains("mf-layout-drawer", "mf-layout-left-drawer"),
+        style=Contains("width: 250px")
+    )
+
+    assert matches(drawer, expected)
+```
+
+**Points clés :**
+- Expliquez pourquoi l'attribut/élément est important (fonctionnalité, HTMX, styling, etc.)
+- Pas besoin de suivre une formulation rigide
+- L'important est la **justification du choix**, pas le format
+
+---
+
+#### **UTR-11.8 : Tests de comptage avec messages explicites**
+
+**Principe :** Quand vous comptez des éléments avec `assert len()`, ajoutez TOUJOURS un message explicite qui explique pourquoi ce nombre est attendu.
+
+**Exemple :**
+```python
+# ✅ BON - message explicatif
+resizers = find(drawer, Div(cls=Contains("mf-resizer-left")))
+assert len(resizers) == 1, "Left drawer should contain exactly one resizer element"
+
+dividers = find(content, Div(cls="divider"))
+assert len(dividers) >= 1, "Groups should be separated by dividers"
+
+# ❌ À ÉVITER - pas de message
+assert len(resizers) == 1
+```
+
+---
+
+#### **AUTRES RÈGLES IMPORTANTES**
+
+---
+
+**Mandatory render test rules:**
+
+1. **Test naming**: Use descriptive names like `test_empty_layout_is_rendered()` not `test_layout_renders_with_all_sections()`
+
+2. **Documentation format**: Every render test MUST have a docstring with:
+   - First line: Brief description of what is being tested
+   - Blank line
+   - Justification section explaining why tested elements matter (see UTR-11.7)
+   - List of important elements/attributes being tested with explanations (in English)
+
+3. **No inline comments**: Do NOT add comments on each line of the expected structure (except for structural clarification in global layout tests like `# left drawer`)
+
+4. **Component testing**: Use `TestObject(ComponentClass)` to test presence of components
+
+5. **Test organization for Controls**: Organize tests into thematic classes:
+   - `TestControlBehaviour`: Tests for control behavior and logic
+   - `TestControlRender`: Tests for control HTML rendering
+
+6. **Fixture usage**: In `TestControlRender`, use a pytest fixture to create the control instance:
+   ```python
+   class TestControlRender:
+       @pytest.fixture
+       def layout(self, root_instance):
+           return Layout(root_instance, app_name="Test App")
+
+       def test_something(self, layout):
+           # layout is injected automatically
+   ```
+
+---
+
+#### **Résumé : Les 8 règles UTR-11**
+
+**Pattern fondamental**
+- **UTR-11.1** : Pattern en trois étapes (extraire → définir expected → comparer)
+
+**Comment chercher**
+- **UTR-11.2** : Privilégier recherche par ID
+- **UTR-11.3** : `find_one()` vs `find()` selon contexte
+
+**Comment spécifier**
+- **UTR-11.4** : Toujours `Contains()` pour `cls` et `style`
+- **UTR-11.5** : `TestIcon()` pour tester la présence d'icônes
+- **UTR-11.6** : `TestScript()` pour JavaScript
+
+**Comment documenter**
+- **UTR-11.7** : Justifier le choix des éléments testés
+- **UTR-11.8** : Messages explicites pour `assert len()`
+
+---
+
+**When proposing render tests:**
+- Reference specific patterns from the documentation
+- Explain why you chose to test certain elements and not others
+- Justify the use of predicates vs exact values
+- Always include justification documentation (see UTR-11.7)
+
+### UTR-12: Test Workflow
+
+1. **Receive code to test** - User provides file path or code section
+2. **Check existing tests** - Look for corresponding test file and read it if it exists
+3. **Analyze code** - Read and understand implementation
+4. **Gap analysis** - If tests exist, identify what's missing; otherwise identify all scenarios
+5. **Propose test plan** - List new/missing tests with brief explanations
+6. **Wait for approval** - User validates the test plan
+7. **Implement tests** - Write all approved tests
+8. **Verify** - Ensure tests follow naming conventions and structure
+9. **Ask before running** - Do NOT automatically run tests with pytest. Ask user first if they want to run the tests.
+
+## Managing Rules
+
+To disable a specific rule, the user can say:
+- "Disable UTR-4" (do not apply the rule about testing Python built-ins)
+- "Enable UTR-4" (re-enable a previously disabled rule)
+
+When a rule is disabled, acknowledge it and adapt behavior accordingly.
+
+## Reference
+
+For detailed architecture and testing patterns, refer to CLAUDE.md in the project root.
+
+## Other Personas
+
+- Use `/developer` to switch to development mode
+- Use `/technical-writer` to switch to documentation mode
+- Use `/reset` to return to default Claude Code mode

CLAUDE.md

@@ -95,6 +95,36 @@ def test_i_cannot_create_command_with_empty_name():
 3. **Wait for validation** that the diagnosis is correct
 4. Only then propose solutions
 
+## Available Personas
+
+This project includes specialized personas (slash commands) for different types of work:
+
+### `/developer` - Development Mode (Default)
+**Use for:** Writing code, implementing features, fixing bugs
+
+Activates the full development workflow with:
+- Options-first approach before coding
+- Step-by-step validation
+- Strict PEP 8 compliance
+- Test-driven development with `test_i_can_xxx` / `test_i_cannot_xxx` patterns
+
+### `/technical-writer` - Documentation Mode
+**Use for:** Writing user-facing documentation
+
+Focused on creating:
+- README sections and examples
+- Usage guides and tutorials
+- Getting started documentation
+- Code examples for end users
+
+**Does NOT handle:**
+- Docstrings (developer responsibility)
+- Internal architecture docs
+- CLAUDE.md updates
+
+### `/reset` - Default Claude Code
+**Use for:** Return to standard Claude Code behavior without personas
+
 ## Development Commands
 
 ### Testing

Makefile

@@ -18,6 +18,7 @@ clean-tests:
 	rm -rf .sesskey
 	rm -rf tests/.sesskey
 	rm -rf tests/*.db
+	rm -rf tests/.myFastHtmlDb
 
 # Alias to clean everything
 clean: clean-build clean-tests

docs/Layout.md

@@ -0,0 +1,583 @@
+# Layout Component
+
+## Introduction
+
+The Layout component provides a complete application structure with fixed header and footer, a scrollable main content
+area, and optional collapsible side drawers. It's designed to be the foundation of your FastHTML application's UI.
+
+**Key features:**
+
+- Fixed header and footer that stay visible while scrolling
+- Collapsible left and right drawers for navigation, tools, or auxiliary content
+- Resizable drawers with drag handles
+- Automatic state persistence per session
+- Single instance per session (singleton pattern)
+
+**Common use cases:**
+
+- Application with navigation sidebar
+- Dashboard with tools panel
+- Admin interface with settings drawer
+- Documentation site with table of contents
+
+## Quick Start
+
+Here's a minimal example showing an application with a navigation sidebar:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.Layout import Layout
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+
+# Create the layout instance
+layout = Layout(parent=root_instance, app_name="My App")
+
+# Add navigation items to the left drawer
+layout.left_drawer.add(
+  mk.mk(Div("Home"), command=Command(...))
+)
+layout.left_drawer.add(
+  mk.mk(Div("About"), command=Command(...))
+)
+layout.left_drawer.add(
+  mk.mk(Div("Contact"), command=Command(...))
+)
+
+# Set the main content
+layout.set_main(
+  Div(
+    H1("Welcome"),
+    P("This is the main content area")
+  )
+)
+
+# Render the layout
+return layout
+```
+
+This creates a complete application layout with:
+
+- A header displaying the app name and drawer toggle button
+- A collapsible left drawer with interactive navigation items
+- A main content area that updates when navigation items are clicked
+- An empty footer
+
+**Note:** Navigation items use commands to update the main content area without page reload. See the Commands section
+below for details.
+
+## Basic Usage
+
+### Creating a Layout
+
+The Layout component is a `SingleInstance`, meaning there's only one instance per session. Create it by providing a
+parent instance and an application name:
+
+```python
+layout = Layout(parent=root_instance, app_name="My Application")
+```
+
+### Content Zones
+
+The Layout provides six content zones where you can add components:
+
+```
+┌──────────────────────────────────────────────────────────┐
+│  Header                                                  │
+│  ┌─────────────────┐              ┌─────────────────┐    │
+│  │  header_left    │              │  header_right   │    │
+│  └─────────────────┘              └─────────────────┘    │
+├─────────┬────────────────────────────────────┬───────────┤
+│         │                                    │           │
+│  left   │                                    │  right    │
+│ drawer  │           Main Content             │  drawer   │
+│         │                                    │           │
+│         │                                    │           │
+├─────────┴────────────────────────────────────┴───────────┤
+│  Footer                                                  │
+│  ┌─────────────────┐              ┌─────────────────┐    │
+│  │  footer_left    │              │  footer_right   │    │
+│  └─────────────────┘              └─────────────────┘    │
+└──────────────────────────────────────────────────────────┘
+```
+
+**Zone details:**
+
+| Zone           | Typical Use                                   |
+|----------------|-----------------------------------------------|
+| `header_left`  | App logo, menu button, breadcrumbs            |
+| `header_right` | User profile, notifications, settings         |
+| `left_drawer`  | Navigation menu, tree view, filters           |
+| `right_drawer` | Tools panel, properties inspector, debug info |
+| `footer_left`  | Copyright, legal links, version               |
+| `footer_right` | Status indicators, connection state           |
+
+### Adding Content to Zones
+
+Use the `.add()` method to add components to any zone:
+
+```python
+# Header
+layout.header_left.add(Div("Logo"))
+layout.header_right.add(Div("User: Admin"))
+
+# Drawers
+layout.left_drawer.add(Div("Navigation"))
+layout.right_drawer.add(Div("Tools"))
+
+# Footer
+layout.footer_left.add(Div("© 2024 My App"))
+layout.footer_right.add(Div("v1.0.0"))
+```
+
+### Setting Main Content
+
+The main content area displays your page content and can be updated dynamically:
+
+```python
+# Set initial content
+layout.set_main(
+  Div(
+    H1("Dashboard"),
+    P("Welcome to your dashboard")
+  )
+)
+
+# Update later (typically via commands)
+layout.set_main(
+  Div(
+    H1("Settings"),
+    P("Configure your preferences")
+  )
+)
+```
+
+### Controlling Drawers
+
+By default, both drawers are visible. The drawer state is managed automatically:
+
+- Users can toggle drawers using the icon buttons in the header
+- Users can resize drawers by dragging the handle
+- Drawer state persists within the session
+
+The initial drawer widths are:
+
+- Left drawer: 250px
+- Right drawer: 250px
+
+These can be adjusted by users and the state is preserved automatically.
+
+## Content System
+
+### Understanding Groups
+
+Each content zone (header_left, header_right, drawers, footer) supports **groups** to organize related items. Groups are
+separated visually by dividers and can have optional labels.
+
+### Adding Content to Groups
+
+When adding content, you can optionally specify a group name:
+
+```python
+# Add items to different groups in the left drawer
+layout.left_drawer.add(Div("Dashboard"), group="main")
+layout.left_drawer.add(Div("Analytics"), group="main")
+layout.left_drawer.add(Div("Settings"), group="preferences")
+layout.left_drawer.add(Div("Profile"), group="preferences")
+```
+
+This creates two groups:
+
+- **main**: Dashboard, Analytics
+- **preferences**: Settings, Profile
+
+A visual divider automatically appears between groups.
+
+### Custom Group Labels
+
+You can provide a custom FastHTML element to display as the group header:
+
+```python
+# Add a styled group header
+layout.left_drawer.add_group(
+  "Navigation",
+  group_ft=Div("MAIN MENU", cls="font-bold text-sm opacity-60 px-2 py-1")
+)
+
+# Then add items to this group
+layout.left_drawer.add(Div("Home"), group="Navigation")
+layout.left_drawer.add(Div("About"), group="Navigation")
+```
+
+### Ungrouped Content
+
+If you don't specify a group, content is added to the default (`None`) group:
+
+```python
+# These items are in the default group
+layout.left_drawer.add(Div("Quick Action 1"))
+layout.left_drawer.add(Div("Quick Action 2"))
+```
+
+### Preventing Duplicates
+
+The Content system automatically prevents adding duplicate items based on their `id` attribute:
+
+```python
+item = Div("Unique Item", id="my-item")
+layout.left_drawer.add(item)
+layout.left_drawer.add(item)  # Ignored - already added
+```
+
+### Group Rendering Options
+
+Groups render differently depending on the zone:
+
+**In drawers** (vertical layout):
+
+- Groups stack vertically
+- Dividers are horizontal lines
+- Group labels appear above their content
+
+**In header/footer** (horizontal layout):
+
+- Groups arrange side-by-side
+- Dividers are vertical lines
+- Group labels are typically hidden
+
+## Advanced Features
+
+### Resizable Drawers
+
+Both drawers can be resized by users via drag handles:
+
+- **Drag handle location**:
+    - Left drawer: Right edge
+    - Right drawer: Left edge
+- **Width constraints**: 150px (minimum) to 600px (maximum)
+- **Persistence**: Resized width is automatically saved in the session state
+
+Users can drag the handle to adjust drawer width. The new width is preserved throughout their session.
+
+### Programmatic Drawer Control
+
+You can control drawers programmatically using commands:
+
+```python
+# Toggle drawer visibility
+toggle_left = layout.commands.toggle_drawer("left")
+toggle_right = layout.commands.toggle_drawer("right")
+
+# Update drawer width
+update_left_width = layout.commands.update_drawer_width("left", width=300)
+update_right_width = layout.commands.update_drawer_width("right", width=350)
+```
+
+These commands are typically used with buttons or other interactive elements:
+
+```python
+# Add a button to toggle the right drawer
+button = mk.button("Toggle Tools", command=layout.commands.toggle_drawer("right"))
+layout.header_right.add(button)
+```
+
+### State Persistence
+
+The Layout automatically persists its state within the user's session:
+
+| State Property       | Description                     | Default |
+|----------------------|---------------------------------|---------|
+| `left_drawer_open`   | Whether left drawer is visible  | `True`  |
+| `right_drawer_open`  | Whether right drawer is visible | `True`  |
+| `left_drawer_width`  | Left drawer width in pixels     | `250`   |
+| `right_drawer_width` | Right drawer width in pixels    | `250`   |
+
+State changes (toggle, resize) are automatically saved and restored within the session.
+
+### Dynamic Content Updates
+
+Content zones can be updated dynamically during the session:
+
+```python
+# Initial setup
+layout.left_drawer.add(Div("Item 1"))
+
+
+# Later, add more items (e.g., in a command handler)
+def add_dynamic_content():
+  layout.left_drawer.add(Div("New Item"), group="dynamic")
+  return layout.left_drawer  # Return updated drawer for HTMX swap
+```
+
+**Note**: When updating content dynamically, you typically return the updated zone to trigger an HTMX swap.
+
+### CSS Customization
+
+The Layout uses CSS classes that you can customize:
+
+| Class                      | Element                          |
+|----------------------------|----------------------------------|
+| `mf-layout`                | Root layout container            |
+| `mf-layout-header`         | Header section                   |
+| `mf-layout-footer`         | Footer section                   |
+| `mf-layout-main`           | Main content area                |
+| `mf-layout-drawer`         | Drawer container                 |
+| `mf-layout-left-drawer`    | Left drawer specifically         |
+| `mf-layout-right-drawer`   | Right drawer specifically        |
+| `mf-layout-drawer-content` | Scrollable content within drawer |
+| `mf-resizer`               | Resize handle                    |
+| `mf-layout-group`          | Content group wrapper            |
+
+You can override these classes in your custom CSS to change colors, spacing, or behavior.
+
+### User Profile Integration
+
+The Layout automatically includes a UserProfile component in the header right area. This component handles user
+authentication display and logout functionality when auth is enabled.
+
+## Examples
+
+### Example 1: Dashboard with Navigation Sidebar
+
+A typical dashboard application with a navigation menu in the left drawer:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.Layout import Layout
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+
+# Create layout
+layout = Layout(parent=root_instance, app_name="Analytics Dashboard")
+
+
+# Navigation menu in left drawer
+def show_dashboard():
+  layout.set_main(Div(H1("Dashboard"), P("Overview of your metrics")))
+  return layout._mk_main()
+
+
+def show_reports():
+  layout.set_main(Div(H1("Reports"), P("Detailed analytics reports")))
+  return layout._mk_main()
+
+
+def show_settings():
+  layout.set_main(Div(H1("Settings"), P("Configure your preferences")))
+  return layout._mk_main()
+
+
+# Add navigation items with groups
+layout.left_drawer.add_group("main", group_ft=Div("MENU", cls="font-bold text-xs px-2 opacity-60"))
+layout.left_drawer.add(mk.mk(Div("Dashboard"), command=Command("nav_dash", "Show dashboard", show_dashboard)),
+                       group="main")
+layout.left_drawer.add(mk.mk(Div("Reports"), command=Command("nav_reports", "Show reports", show_reports)),
+                       group="main")
+
+layout.left_drawer.add_group("config", group_ft=Div("CONFIGURATION", cls="font-bold text-xs px-2 opacity-60"))
+layout.left_drawer.add(mk.mk(Div("Settings"), command=Command("nav_settings", "Show settings", show_settings)),
+                       group="config")
+
+# Header content
+layout.header_left.add(Div("📊 Analytics", cls="font-bold"))
+
+# Footer
+layout.footer_left.add(Div("© 2024 Analytics Co."))
+layout.footer_right.add(Div("v1.0.0"))
+
+# Set initial main content
+layout.set_main(Div(H1("Dashboard"), P("Overview of your metrics")))
+```
+
+### Example 2: Development Tool with Debug Panel
+
+An application with development tools in the right drawer:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.Layout import Layout
+from myfasthtml.controls.helpers import mk
+
+# Create layout
+layout = Layout(parent=root_instance, app_name="Dev Tools")
+
+# Main content: code editor
+layout.set_main(
+  Div(
+    H2("Code Editor"),
+    Textarea("# Write your code here", rows=20, cls="w-full font-mono")
+  )
+)
+
+# Right drawer: debug and tools
+layout.right_drawer.add_group("debug", group_ft=Div("DEBUG INFO", cls="font-bold text-xs px-2 opacity-60"))
+layout.right_drawer.add(Div("Console output here..."), group="debug")
+layout.right_drawer.add(Div("Variables: x=10, y=20"), group="debug")
+
+layout.right_drawer.add_group("tools", group_ft=Div("TOOLS", cls="font-bold text-xs px-2 opacity-60"))
+layout.right_drawer.add(Button("Run Code"), group="tools")
+layout.right_drawer.add(Button("Clear Console"), group="tools")
+
+# Header
+layout.header_left.add(Div("DevTools IDE"))
+layout.header_right.add(Button("Save"))
+```
+
+### Example 3: Minimal Layout (Main Content Only)
+
+A simple layout without drawers, focusing only on main content:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.Layout import Layout
+
+# Create layout
+layout = Layout(parent=root_instance, app_name="Simple Blog")
+
+# Header
+layout.header_left.add(Div("My Blog", cls="text-xl font-bold"))
+layout.header_right.add(A("About", href="/about"))
+
+# Main content
+layout.set_main(
+  Article(
+    H1("Welcome to My Blog"),
+    P("This is a simple blog layout without side drawers."),
+    P("The focus is on the content in the center.")
+  )
+)
+
+# Footer
+layout.footer_left.add(Div("© 2024 Blog Author"))
+layout.footer_right.add(A("RSS", href="/rss"))
+
+# Note: Drawers are present but can be collapsed by users if not needed
+```
+
+### Example 4: Dynamic Content Loading
+
+Loading content dynamically based on user interaction:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.Layout import Layout
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+
+layout = Layout(parent=root_instance, app_name="Dynamic App")
+
+
+# Function that loads content dynamically
+def load_page(page_name):
+  # Simulate loading different content
+  content = {
+      "home": Div(H1("Home"), P("Welcome to the home page")),
+      "profile": Div(H1("Profile"), P("User profile information")),
+      "settings": Div(H1("Settings"), P("Application settings")),
+  }
+  layout.set_main(content.get(page_name, Div("Page not found")))
+  return layout._mk_main()
+
+
+# Create navigation commands
+pages = ["home", "profile", "settings"]
+for page in pages:
+  cmd = Command(f"load_{page}", f"Load {page} page", load_page, page)
+  layout.left_drawer.add(
+    mk.mk(Div(page.capitalize()), command=cmd)
+  )
+
+# Set initial content
+layout.set_main(Div(H1("Home"), P("Welcome to the home page")))
+```
+
+---
+
+## Developer Reference
+
+This section contains technical details for developers working on the Layout component itself.
+
+### State
+
+The Layout component maintains the following state properties:
+
+| Name                 | Type    | Description                      | Default |
+|----------------------|---------|----------------------------------|---------|
+| `left_drawer_open`   | boolean | True if the left drawer is open  | True    |
+| `right_drawer_open`  | boolean | True if the right drawer is open | True    |
+| `left_drawer_width`  | integer | Width of the left drawer         | 250     |
+| `right_drawer_width` | integer | Width of the right drawer        | 250     |
+
+### Commands
+
+Available commands for programmatic control:
+
+| Name                                    | Description                                                                            |
+|-----------------------------------------|----------------------------------------------------------------------------------------|
+| `toggle_drawer(side)`                   | Toggles the drawer on the specified side                                               |
+| `update_drawer_width(side, width=None)` | Updates the drawer width on the specified side. The width is given by the HTMX request |
+
+### Public Methods
+
+| Method              | Description                 |
+|---------------------|-----------------------------|
+| `set_main(content)` | Sets the main content area  |
+| `render()`          | Renders the complete layout |
+
+### High Level Hierarchical Structure
+
+```
+Div(id="layout")
+├── Header
+│   ├── Div(id="layout_hl")
+│   │   ├── Icon                # Left drawer icon button
+│   │   └── Div                 # Left content for the header
+│   └── Div(id="layout_hr")
+│       ├── Div                 # Right content for the header
+│       └── UserProfile         # user profile icon button
+├── Div                         # Left Drawer
+├── Main                        # Main content
+├── Div                         # Right Drawer
+├── Footer                      # Footer
+└── Script                      # To initialize the resizing
+```
+
+### Element IDs
+
+| Name        | Description                         |
+|-------------|-------------------------------------|
+| `layout`    | Root layout container (singleton)   |
+| `layout_h`  | Header section (not currently used) |
+| `layout_hl` | Header left side                    |
+| `layout_hr` | Header right side                   |
+| `layout_f`  | Footer section (not currently used) |
+| `layout_fl` | Footer left side                    |
+| `layout_fr` | Footer right side                   |
+| `layout_ld` | Left drawer                         |
+| `layout_rd` | Right drawer                        |
+
+### Internal Methods
+
+These methods are used internally for rendering:
+
+| Method                    | Description                                            |
+|---------------------------|--------------------------------------------------------|
+| `_mk_header()`            | Renders the header component                           |
+| `_mk_footer()`            | Renders the footer component                           |
+| `_mk_main()`              | Renders the main content area                          |
+| `_mk_left_drawer()`       | Renders the left drawer                                |
+| `_mk_right_drawer()`      | Renders the right drawer                               |
+| `_mk_left_drawer_icon()`  | Renders the left drawer toggle icon                    |
+| `_mk_right_drawer_icon()` | Renders the right drawer toggle icon                   |
+| `_mk_content_wrapper()`   | Static method to wrap content with groups and dividers |
+
+### Content Class
+
+The `Layout.Content` nested class manages content zones:
+
+| Method                            | Description                                              |
+|-----------------------------------|----------------------------------------------------------|
+| `add(content, group=None)`        | Adds content to a group, prevents duplicates based on ID |
+| `add_group(group, group_ft=None)` | Creates a new group with optional custom header element  |
+| `get_content()`                   | Returns dictionary of groups and their content           |
+| `get_groups()`                    | Returns list of (group_name, group_ft) tuples            |

docs/TreeView.md

@@ -0,0 +1,596 @@
+# TreeView Component
+
+## Introduction
+
+The TreeView component provides an interactive hierarchical data visualization with full CRUD operations. It's designed for displaying tree-structured data like file systems, organizational charts, or navigation menus with inline editing capabilities.
+
+**Key features:**
+
+- Expand/collapse nodes with visual indicators
+- Add child and sibling nodes dynamically
+- Inline rename with keyboard support (ESC to cancel)
+- Delete nodes (only leaf nodes without children)
+- Node selection tracking
+- Persistent state per session
+- Configurable icons per node type
+
+**Common use cases:**
+
+- File/folder browser
+- Category/subcategory management
+- Organizational hierarchy viewer
+- Navigation menu builder
+- Document outline editor
+
+## Quick Start
+
+Here's a minimal example showing a file system tree:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+
+# Create TreeView instance
+tree = TreeView(parent=root_instance, _id="file-tree")
+
+# Add root folder
+root = TreeNode(id="root", label="Documents", type="folder")
+tree.add_node(root)
+
+# Add some files
+file1 = TreeNode(id="file1", label="report.pdf", type="file")
+file2 = TreeNode(id="file2", label="budget.xlsx", type="file")
+tree.add_node(file1, parent_id="root")
+tree.add_node(file2, parent_id="root")
+
+# Expand root to show children
+tree.expand_all()
+
+# Render the tree
+return tree
+```
+
+This creates an interactive tree where users can:
+- Click chevrons to expand/collapse folders
+- Click labels to select items
+- Use action buttons (visible on hover) to add, rename, or delete nodes
+
+**Note:** All interactions use commands and update via HTMX without page reload.
+
+## Basic Usage
+
+### Creating a TreeView
+
+TreeView is a `MultipleInstance`, allowing multiple trees per session. Create it with a parent instance:
+
+```python
+tree = TreeView(parent=root_instance, _id="my-tree")
+```
+
+### TreeNode Structure
+
+Nodes are represented by the `TreeNode` dataclass:
+
+```python
+from myfasthtml.controls.TreeView import TreeNode
+
+node = TreeNode(
+    id="unique-id",           # Auto-generated UUID if not provided
+    label="Node Label",       # Display text
+    type="default",           # Type for icon mapping
+    parent=None,              # Parent node ID (None for root)
+    children=[]               # List of child node IDs
+)
+```
+
+### Adding Nodes
+
+Add nodes using the `add_node()` method:
+
+```python
+# Add root node
+root = TreeNode(id="root", label="Root", type="folder")
+tree.add_node(root)
+
+# Add child node
+child = TreeNode(label="Child 1", type="item")
+tree.add_node(child, parent_id="root")
+
+# Add with specific position
+sibling = TreeNode(label="Child 2", type="item")
+tree.add_node(sibling, parent_id="root", insert_index=0)  # Insert at start
+```
+
+### Visual Structure
+
+```
+TreeView
+├── Root Node 1
+│   ├── [>] Child 1-1        # Collapsed node with children
+│   ├── [ ] Child 1-2        # Leaf node (no children)
+│   └── [v] Child 1-3        # Expanded node
+│       ├── [ ] Grandchild
+│       └── [ ] Grandchild
+└── Root Node 2
+    └── [>] Child 2-1
+```
+
+**Legend:**
+- `[>]` - Collapsed node (has children)
+- `[v]` - Expanded node (has children)
+- `[ ]` - Leaf node (no children)
+
+### Expanding Nodes
+
+Control node expansion programmatically:
+
+```python
+# Expand all nodes with children
+tree.expand_all()
+
+# Expand specific nodes by adding to opened list
+tree._state.opened.append("node-id")
+```
+
+**Note:** Users can also toggle nodes by clicking the chevron icon.
+
+## Interactive Features
+
+### Node Selection
+
+Users can select nodes by clicking on labels. The selected node is visually highlighted:
+
+```python
+# Programmatically select a node
+tree._state.selected = "node-id"
+
+# Check current selection
+current = tree._state.selected
+```
+
+### Adding Nodes
+
+Users can add nodes via action buttons (visible on hover):
+
+**Add Child:**
+- Adds a new node as a child of the target node
+- Automatically expands the parent
+- Creates node with same type as parent
+
+**Add Sibling:**
+- Adds a new node next to the target node (same parent)
+- Inserts after the target node
+- Cannot add sibling to root nodes
+
+```python
+# Programmatically add child
+tree._add_child(parent_id="root", new_label="New Child")
+
+# Programmatically add sibling
+tree._add_sibling(node_id="child1", new_label="New Sibling")
+```
+
+### Renaming Nodes
+
+Users can rename nodes via the edit button:
+
+1. Click the edit icon (visible on hover)
+2. Input field appears with current label
+3. Press Enter to save (triggers command)
+4. Press ESC to cancel (keyboard shortcut)
+
+```python
+# Programmatically start rename
+tree._start_rename("node-id")
+
+# Save rename
+tree._save_rename("node-id", "New Label")
+
+# Cancel rename
+tree._cancel_rename()
+```
+
+### Deleting Nodes
+
+Users can delete nodes via the delete button:
+
+**Restrictions:**
+- Can only delete leaf nodes (no children)
+- Attempting to delete a node with children raises an error
+- Deleted node is removed from parent's children list
+
+```python
+# Programmatically delete node
+tree._delete_node("node-id")  # Raises ValueError if node has children
+```
+
+## Content System
+
+### Node Types and Icons
+
+Assign types to nodes for semantic grouping and custom icon display:
+
+```python
+# Define node types
+root = TreeNode(label="Project", type="project")
+folder = TreeNode(label="src", type="folder")
+file = TreeNode(label="main.py", type="python-file")
+
+# Configure icons for types
+tree.set_icon_config({
+    "project": "fluent.folder_open",
+    "folder": "fluent.folder",
+    "python-file": "fluent.document_python"
+})
+```
+
+**Note:** Icon configuration is stored in state and persists within the session.
+
+### Hierarchical Organization
+
+Nodes automatically maintain parent-child relationships:
+
+```python
+# Get node's children
+node = tree._state.items["node-id"]
+child_ids = node.children
+
+# Get node's parent
+parent_id = node.parent
+
+# Navigate tree programmatically
+for child_id in node.children:
+    child_node = tree._state.items[child_id]
+    print(child_node.label)
+```
+
+### Finding Root Nodes
+
+Root nodes are nodes without a parent:
+
+```python
+root_nodes = [
+    node_id for node_id, node in tree._state.items.items()
+    if node.parent is None
+]
+```
+
+## Advanced Features
+
+### Keyboard Shortcuts
+
+TreeView includes keyboard support for common operations:
+
+| Key | Action |
+|-----|--------|
+| `ESC` | Cancel rename operation |
+
+Additional shortcuts can be added via the Keyboard component:
+
+```python
+from myfasthtml.controls.Keyboard import Keyboard
+
+tree = TreeView(parent=root_instance)
+# ESC handler is automatically included for cancel rename
+```
+
+### State Management
+
+TreeView maintains persistent state within the session:
+
+| State Property | Type | Description |
+|----------------|------|-------------|
+| `items` | `dict[str, TreeNode]` | All nodes indexed by ID |
+| `opened` | `list[str]` | IDs of expanded nodes |
+| `selected` | `str \| None` | Currently selected node ID |
+| `editing` | `str \| None` | Node being renamed (if any) |
+| `icon_config` | `dict[str, str]` | Type-to-icon mapping |
+
+### Dynamic Updates
+
+TreeView updates are handled via commands that return the updated tree:
+
+```python
+# Commands automatically target the tree for HTMX swap
+cmd = tree.commands.toggle_node("node-id")
+# When executed, returns updated TreeView with new state
+```
+
+### CSS Customization
+
+TreeView uses CSS classes for styling:
+
+| Class | Element |
+|-------|---------|
+| `mf-treeview` | Root container |
+| `mf-treenode-container` | Container for node and its children |
+| `mf-treenode` | Individual node row |
+| `mf-treenode.selected` | Selected node highlight |
+| `mf-treenode-label` | Node label text |
+| `mf-treenode-input` | Input field during rename |
+| `mf-treenode-actions` | Action buttons container (hover) |
+
+You can override these classes to customize appearance:
+
+```css
+.mf-treenode.selected {
+    background-color: #e0f2fe;
+    border-left: 3px solid #0284c7;
+}
+
+.mf-treenode-actions {
+    opacity: 0;
+    transition: opacity 0.2s;
+}
+
+.mf-treenode:hover .mf-treenode-actions {
+    opacity: 1;
+}
+```
+
+## Examples
+
+### Example 1: File System Browser
+
+A file/folder browser with different node types:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+
+# Create tree
+tree = TreeView(parent=root_instance, _id="file-browser")
+
+# Configure icons
+tree.set_icon_config({
+    "folder": "fluent.folder",
+    "python": "fluent.document_python",
+    "text": "fluent.document_text"
+})
+
+# Build file structure
+root = TreeNode(id="root", label="my-project", type="folder")
+tree.add_node(root)
+
+src = TreeNode(id="src", label="src", type="folder")
+tree.add_node(src, parent_id="root")
+
+main = TreeNode(label="main.py", type="python")
+utils = TreeNode(label="utils.py", type="python")
+tree.add_node(main, parent_id="src")
+tree.add_node(utils, parent_id="src")
+
+readme = TreeNode(label="README.md", type="text")
+tree.add_node(readme, parent_id="root")
+
+# Expand to show structure
+tree.expand_all()
+
+return tree
+```
+
+### Example 2: Category Management
+
+Managing product categories with inline editing:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+
+tree = TreeView(parent=root_instance, _id="categories")
+
+# Root categories
+electronics = TreeNode(id="elec", label="Electronics", type="category")
+tree.add_node(electronics)
+
+# Subcategories
+computers = TreeNode(label="Computers", type="subcategory")
+phones = TreeNode(label="Phones", type="subcategory")
+tree.add_node(computers, parent_id="elec")
+tree.add_node(phones, parent_id="elec")
+
+# Products (leaf nodes)
+laptop = TreeNode(label="Laptops", type="product")
+desktop = TreeNode(label="Desktops", type="product")
+tree.add_node(laptop, parent_id=computers.id)
+tree.add_node(desktop, parent_id=computers.id)
+
+tree.expand_all()
+return tree
+```
+
+### Example 3: Document Outline Editor
+
+Building a document outline with headings:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+
+tree = TreeView(parent=root_instance, _id="outline")
+
+# Document structure
+doc = TreeNode(id="doc", label="My Document", type="document")
+tree.add_node(doc)
+
+# Chapters
+ch1 = TreeNode(id="ch1", label="Chapter 1: Introduction", type="heading1")
+ch2 = TreeNode(id="ch2", label="Chapter 2: Methods", type="heading1")
+tree.add_node(ch1, parent_id="doc")
+tree.add_node(ch2, parent_id="doc")
+
+# Sections
+sec1_1 = TreeNode(label="1.1 Background", type="heading2")
+sec1_2 = TreeNode(label="1.2 Objectives", type="heading2")
+tree.add_node(sec1_1, parent_id="ch1")
+tree.add_node(sec1_2, parent_id="ch1")
+
+# Subsections
+subsec = TreeNode(label="1.1.1 Historical Context", type="heading3")
+tree.add_node(subsec, parent_id=sec1_1.id)
+
+tree.expand_all()
+return tree
+```
+
+### Example 4: Dynamic Tree with Event Handling
+
+Responding to tree events with custom logic:
+
+```python
+from fasthtml.common import *
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+
+tree = TreeView(parent=root_instance, _id="dynamic-tree")
+
+# Initial structure
+root = TreeNode(id="root", label="Tasks", type="folder")
+tree.add_node(root)
+
+# Function to handle selection
+def on_node_selected(node_id):
+    # Custom logic when node is selected
+    node = tree._state.items[node_id]
+    tree._select_node(node_id)
+
+    # Update a detail panel elsewhere in the UI
+    return Div(
+        H3(f"Selected: {node.label}"),
+        P(f"Type: {node.type}"),
+        P(f"Children: {len(node.children)}")
+    )
+
+# Override select command with custom handler
+# (In practice, you'd extend the Commands class or use event callbacks)
+
+tree.expand_all()
+return tree
+```
+
+---
+
+## Developer Reference
+
+This section contains technical details for developers working on the TreeView component itself.
+
+### State
+
+The TreeView component maintains the following state properties:
+
+| Name | Type | Description | Default |
+|------|------|-------------|---------|
+| `items` | `dict[str, TreeNode]` | All nodes indexed by ID | `{}` |
+| `opened` | `list[str]` | Expanded node IDs | `[]` |
+| `selected` | `str \| None` | Selected node ID | `None` |
+| `editing` | `str \| None` | Node being renamed | `None` |
+| `icon_config` | `dict[str, str]` | Type-to-icon mapping | `{}` |
+
+### Commands
+
+Available commands for programmatic control:
+
+| Name | Description |
+|------|-------------|
+| `toggle_node(node_id)` | Toggle expand/collapse state |
+| `add_child(parent_id)` | Add child node to parent |
+| `add_sibling(node_id)` | Add sibling node after target |
+| `start_rename(node_id)` | Enter rename mode for node |
+| `save_rename(node_id)` | Save renamed node label |
+| `cancel_rename()` | Cancel rename operation |
+| `delete_node(node_id)` | Delete node (if no children) |
+| `select_node(node_id)` | Select a node |
+
+All commands automatically target the TreeView component for HTMX updates.
+
+### Public Methods
+
+| Method | Description |
+|--------|-------------|
+| `add_node(node, parent_id, insert_index)` | Add a node to the tree |
+| `expand_all()` | Expand all nodes with children |
+| `set_icon_config(config)` | Configure icons for node types |
+| `render()` | Render the complete TreeView |
+
+### TreeNode Dataclass
+
+```python
+@dataclass
+class TreeNode:
+    id: str                      # Unique identifier (auto-generated UUID)
+    label: str = ""              # Display text
+    type: str = "default"        # Node type for icon mapping
+    parent: Optional[str] = None # Parent node ID
+    children: list[str] = []     # Child node IDs
+```
+
+### High Level Hierarchical Structure
+
+```
+Div(id="treeview", cls="mf-treeview")
+├── Div(cls="mf-treenode-container", data-node-id="root1")
+│   ├── Div(cls="mf-treenode")
+│   │   ├── Icon                        # Toggle chevron
+│   │   ├── Span(cls="mf-treenode-label") | Input(cls="mf-treenode-input")
+│   │   └── Div(cls="mf-treenode-actions")
+│   │       ├── Icon                    # Add child
+│   │       ├── Icon                    # Rename
+│   │       └── Icon                    # Delete
+│   └── Div(cls="mf-treenode-container")  # Child nodes (if expanded)
+│       └── ...
+├── Div(cls="mf-treenode-container", data-node-id="root2")
+│   └── ...
+└── Keyboard                            # ESC handler
+```
+
+### Element IDs and Attributes
+
+| Attribute | Element | Description |
+|-----------|---------|-------------|
+| `id` | Root Div | TreeView component ID |
+| `data-node-id` | Node container | Node's unique ID |
+
+### Internal Methods
+
+These methods are used internally for rendering and state management:
+
+| Method | Description |
+|--------|-------------|
+| `_toggle_node(node_id)` | Toggle expand/collapse state |
+| `_add_child(parent_id, new_label)` | Add child node implementation |
+| `_add_sibling(node_id, new_label)` | Add sibling node implementation |
+| `_start_rename(node_id)` | Enter rename mode |
+| `_save_rename(node_id, node_label)` | Save renamed node |
+| `_cancel_rename()` | Cancel rename operation |
+| `_delete_node(node_id)` | Delete node if no children |
+| `_select_node(node_id)` | Select a node |
+| `_render_action_buttons(node_id)` | Render hover action buttons |
+| `_render_node(node_id, level)` | Recursively render node and children |
+
+### Commands Class
+
+The `Commands` nested class provides command factory methods:
+
+| Method | Returns |
+|--------|---------|
+| `toggle_node(node_id)` | Command to toggle node |
+| `add_child(parent_id)` | Command to add child |
+| `add_sibling(node_id)` | Command to add sibling |
+| `start_rename(node_id)` | Command to start rename |
+| `save_rename(node_id)` | Command to save rename |
+| `cancel_rename()` | Command to cancel rename |
+| `delete_node(node_id)` | Command to delete node |
+| `select_node(node_id)` | Command to select node |
+
+All commands are automatically configured with HTMX targeting.
+
+### Integration with Keyboard Component
+
+TreeView includes a Keyboard component for ESC key handling:
+
+```python
+Keyboard(self, {"esc": self.commands.cancel_rename()}, _id="-keyboard")
+```
+
+This enables users to press ESC to cancel rename operations without clicking.

docs/testing_rendered_components.md

@@ -0,0 +1,895 @@
+# Testing Rendered Components with Matcher
+
+## Introduction
+
+When testing FastHTML components, you need to verify that the HTML they generate is correct. Traditional approaches like string comparison are fragile and hard to maintain. The matcher module provides two powerful functions that make component testing simple and reliable:
+
+- **`matches(actual, expected)`** - Validates that a rendered element matches your expectations
+- **`find(ft, expected)`** - Searches for specific elements within an HTML tree
+
+**Key principle**: Test only what matters. The matcher compares only the elements and attributes you explicitly define in your `expected` pattern, ignoring everything else.
+
+### Why use matcher?
+
+**Without matcher:**
+```python
+# Fragile - breaks if whitespace or attribute order changes
+assert str(component.render()) == '<div id="x" class="y"><p>Text</p></div>'
+```
+
+**With matcher:**
+```python
+# Robust - tests only what matters
+from myfasthtml.test.matcher import matches
+from fasthtml.common import Div, P
+
+actual = component.render()
+expected = Div(P("Text"))
+matches(actual, expected)  # Passes - ignores id and class
+```
+
+---
+
+## Part 1: Function Reference
+
+### matches() - Validate Elements
+
+#### Purpose
+
+`matches()` validates that a rendered element structure corresponds exactly to an expected pattern. It's the primary tool for testing component rendering.
+
+**When to use it:**
+- Verifying component output in tests
+- Checking HTML structure
+- Validating attributes and content
+
+#### Basic Syntax
+
+```python
+from myfasthtml.test.matcher import matches
+
+matches(actual, expected)
+```
+
+- **`actual`**: The element to test (usually from `component.render()`)
+- **`expected`**: The pattern to match against (only include what you want to test)
+- **Returns**: `True` if matches, raises `AssertionError` if not
+
+#### Simple Examples
+
+**Example 1: Basic structure matching**
+
+```python
+from myfasthtml.test.matcher import matches
+from fasthtml.common import Div, P
+
+# The actual rendered element
+actual = Div(P("Hello World"), id="container", cls="main")
+
+# Expected pattern - tests only the structure
+expected = Div(P("Hello World"))
+
+matches(actual, expected)  # ✅ Passes - id and cls are ignored
+```
+
+**Example 2: Testing specific attributes**
+
+```python
+from fasthtml.common import Button
+
+actual = Button("Click me",
+                id="btn-1",
+                cls="btn btn-primary",
+                hx_post="/submit",
+                hx_target="#result")
+
+# Test only the HTMX attribute we care about
+expected = Button("Click me", hx_post="/submit")
+
+matches(actual, expected)  # ✅ Passes
+```
+
+**Example 3: Nested structure**
+
+```python
+from fasthtml.common import Div, H1, Form, Input, Button
+
+actual = Div(
+    H1("Registration Form"),
+    Form(
+        Input(name="email", type="email"),
+        Input(name="password", type="password"),
+        Button("Submit", type="submit")
+    ),
+    id="page",
+    cls="container"
+)
+
+# Test only the important parts
+expected = Div(
+    H1("Registration Form"),
+    Form(
+        Input(name="email"),
+        Button("Submit")
+    )
+)
+
+matches(actual, expected)  # ✅ Passes - ignores password field and attributes
+```
+
+#### Predicates Reference
+
+Predicates allow flexible validation when you don't know the exact value but want to validate a pattern.
+
+##### AttrPredicate - For attribute values
+
+**Contains(value)** - Attribute contains the value
+
+```python
+from myfasthtml.test.matcher import Contains
+from fasthtml.common import Div
+
+actual = Div(cls="container main-content active")
+expected = Div(cls=Contains("main-content"))
+
+matches(actual, expected)  # ✅ Passes
+```
+
+**StartsWith(value)** - Attribute starts with the value
+
+```python
+from myfasthtml.test.matcher import StartsWith
+from fasthtml.common import Input
+
+actual = Input(id="input-username-12345")
+expected = Input(id=StartsWith("input-username"))
+
+matches(actual, expected)  # ✅ Passes
+```
+
+**DoesNotContain(value)** - Attribute does not contain the value
+
+```python
+from myfasthtml.test.matcher import DoesNotContain
+from fasthtml.common import Div
+
+actual = Div(cls="container active")
+expected = Div(cls=DoesNotContain("disabled"))
+
+matches(actual, expected)  # ✅ Passes
+```
+
+**AnyValue()** - Attribute exists with any non-None value
+
+```python
+from myfasthtml.test.matcher import AnyValue
+from fasthtml.common import Button
+
+actual = Button("Click", data_action="submit-form", data_id="123")
+expected = Button("Click", data_action=AnyValue())
+
+matches(actual, expected)  # ✅ Passes - just checks data_action exists
+```
+
+##### ChildrenPredicate - For element children
+
+**Empty()** - Element has no children and no attributes
+
+```python
+from myfasthtml.test.matcher import Empty
+from fasthtml.common import Div
+
+actual = Div()
+expected = Div(Empty())
+
+matches(actual, expected)  # ✅ Passes
+```
+
+**NoChildren()** - Element has no children (but can have attributes)
+
+```python
+from myfasthtml.test.matcher import NoChildren
+from fasthtml.common import Div
+
+actual = Div(id="container", cls="empty")
+expected = Div(NoChildren())
+
+matches(actual, expected)  # ✅ Passes - has attributes but no children
+```
+
+**AttributeForbidden(attr_name)** - Attribute must not be present
+
+```python
+from myfasthtml.test.matcher import AttributeForbidden
+from fasthtml.common import Button
+
+actual = Button("Click me")
+expected = Button("Click me", AttributeForbidden("disabled"))
+
+matches(actual, expected)  # ✅ Passes - disabled attribute is not present
+```
+
+#### Error Messages Explained
+
+When a test fails, `matches()` provides a visual diff showing exactly where the problem is:
+
+```python
+from fasthtml.common import Div, Button
+
+actual = Div(Button("Submit", cls="btn-primary"), id="form")
+expected = Div(Button("Cancel", cls="btn-secondary"))
+
+matches(actual, expected)
+```
+
+**Error output:**
+```
+Path  : 'div.button'
+Error : The values are different
+
+(div "id"="form"           | (div
+  (button "cls"="btn-prim  |   (button "cls"="btn-seco
+          ^^^^^^^^^^^^^^^^ |           
+    "Submit")              |     "Cancel")
+    ^^^^^^^                |   
+)                          | )
+```
+
+**Reading the error:**
+- **Left side**: Actual element
+- **Right side**: Expected pattern
+- **`^^^` markers**: Highlight differences 'only on the left side', the right side (the expected pattern) is always correct
+- **Path**: Shows location in the tree (`div.button` = button inside div)
+
+---
+
+### find() - Search Elements
+
+#### Purpose
+
+`find()` searches for all elements matching a pattern within an HTML tree. It's useful when you need to verify the presence of specific elements without knowing their exact position. Or when you want to validate (using matches) a subset of elements.
+
+**When to use it:**
+- Finding elements by attributes
+- Verifying element count
+- Extracting elements for further validation
+- Testing without strict hierarchy requirements
+
+#### Basic Syntax
+
+```python
+from myfasthtml.test.matcher import find
+
+results = find(ft, expected)
+```
+
+- **`ft`**: Element or list of elements to search in
+- **`expected`**: Pattern to match, follows the same syntax and rules as `matches()`
+- **Returns**: List of all matching elements
+- **Raises**: `AssertionError` if no matches found
+
+#### Simple Examples
+
+**Example 1: Find all elements of a type**
+
+```python
+from myfasthtml.test.matcher import find
+from fasthtml.common import Div, P
+
+page = Div(
+    Div(P("First paragraph")),
+    Div(P("Second paragraph")),
+    P("Third paragraph")
+)
+
+# Find all paragraphs
+paragraphs = find(page, P())
+
+assert len(paragraphs) == 3
+```
+
+**Example 2: Find by attribute**
+
+```python
+from fasthtml.common import Div, Button
+from myfasthtml.test.matcher import find
+
+page = Div(
+    Button("Cancel", cls="btn-secondary"),
+    Div(Button("Submit", cls="btn-primary", id="submit"))
+)
+
+# Find the primary button
+primary_buttons = find(page, Button(cls="btn-primary"))
+
+assert len(primary_buttons) == 1
+assert primary_buttons[0].attrs["id"] == "submit"
+```
+
+**Example 3: Find nested structure**
+
+```python
+from fasthtml.common import Div, Form, Input
+
+page = Div(
+    Div(Input(name="search")),
+    Form(
+        Input(name="email", type="email"),
+        Input(name="password", type="password")
+    )
+)
+
+# Find all email inputs
+email_inputs = find(page, Input(type="email"))
+
+assert len(email_inputs) == 1
+assert email_inputs[0].attrs["name"] == "email"
+```
+
+**Example 4: Search in a list**
+
+```python
+from fasthtml.common import Div, P, Span
+
+elements = [
+    Div(P("First")),
+    Div(P("Second")),
+    Span(P("Third"))
+]
+
+# Find all paragraphs across all elements
+all_paragraphs = find(elements, P())
+
+assert len(all_paragraphs) == 3
+```
+
+#### Common Patterns
+
+**Verify element count:**
+
+```python
+buttons = find(page, Button())
+assert len(buttons) == 3, f"Expected 3 buttons, found {len(buttons)}"
+```
+
+**Check element exists:**
+
+```python
+submit_buttons = find(page, Button(type="submit"))
+assert len(submit_buttons) > 0, "No submit button found"
+```
+
+**Extract for further testing:**
+
+```python
+form = find(page, Form())[0]  # Get first form
+inputs = find(form, Input())   # Find inputs within form
+assert all(inp.attrs.get("type") in ["text", "email"] for inp in inputs)
+```
+
+**Handle missing elements:**
+
+```python
+try:
+    admin_section = find(page, Div(id="admin"))
+    print("Admin section found")
+except AssertionError:
+    print("Admin section not present")
+```
+
+---
+
+## Part 2: Testing Rendered Components Guide
+
+This section provides practical patterns for testing different aspects of rendered components.
+
+### 1. Testing Element Structure
+
+**Goal**: Verify the hierarchy and organization of elements.
+
+**Pattern**: Use `matches()` with only the structural elements you care about.
+
+```python
+from myfasthtml.test.matcher import matches
+from fasthtml.common import Div, Header, Nav, Main, Footer
+
+# Your component renders a page layout
+actual = page_component.render()
+
+# Test only the main structure
+expected = Div(
+    Header(Nav()),
+    Main(),
+    Footer()
+)
+
+matches(actual, expected)
+```
+
+**Tip**: Don't include every single child element. Focus on the important structural elements.
+
+### 2. Testing Attributes
+
+**Goal**: Verify that specific attributes are set correctly.
+
+**Pattern**: Include only the attributes you want to test.
+
+```python
+from fasthtml.common import Button
+
+# Component renders a button with HTMX
+actual = button_component.render()
+
+# Test only HTMX attributes
+expected = Button(
+    hx_post="/api/submit",
+    hx_target="#result",
+    hx_swap="innerHTML"
+)
+
+matches(actual, expected)
+```
+
+**With predicates for dynamic values:**
+
+```python
+from myfasthtml.test.matcher import StartsWith
+
+# Test that id follows a pattern
+expected = Button(id=StartsWith("btn-"))
+matches(actual, expected)
+```
+
+### 3. Testing Content
+
+**Goal**: Verify text content in elements.
+
+**Pattern**: Match elements with their text content.
+
+```python
+from fasthtml.common import Div, H1, P
+
+actual = article_component.render()
+
+expected = Div(
+    H1("Article Title"),
+    P("First paragraph content")
+)
+
+matches(actual, expected)
+```
+
+**Partial content matching:**
+
+```python
+from myfasthtml.test.matcher import Contains
+
+# Check that paragraph contains key phrase
+expected = P(Contains("important information"))
+matches(actual, expected)
+```
+
+### 4. Testing with Predicates
+
+**Goal**: Validate patterns rather than exact values.
+
+**Pattern**: Use predicates for flexibility.
+
+**Example: Testing generated IDs**
+
+```python
+from myfasthtml.test.matcher import StartsWith, AnyValue
+from fasthtml.common import Div
+
+# Component generates unique IDs
+actual = widget_component.render()
+
+expected = Div(
+    id=StartsWith("widget-"),
+    data_timestamp=AnyValue()  # Just check it exists
+)
+
+matches(actual, expected)
+```
+
+**Example: Testing CSS classes**
+
+```python
+from myfasthtml.test.matcher import Contains
+from fasthtml.common import Button
+
+actual = dynamic_button.render()
+
+# Check button has 'active' class among others
+expected = Button(cls=Contains("active"))
+matches(actual, expected)
+```
+
+**Example: Forbidden attributes**
+
+```python
+from myfasthtml.test.matcher import AttributeForbidden
+from fasthtml.common import Input
+
+# Verify input is NOT disabled
+actual = input_component.render()
+
+expected = Input(
+    name="username",
+    AttributeForbidden("disabled")
+)
+
+matches(actual, expected)
+```
+
+### 5. Combining matches() and find()
+
+**Goal**: First find elements, then validate them in detail.
+
+**Pattern**: Use `find()` to locate, then `matches()` to validate.
+
+**Example: Testing a form**
+
+```python
+from myfasthtml.test.matcher import find, matches
+from fasthtml.common import Form, Input, Button
+
+# Render a complex page
+actual = page_component.render()
+
+# Step 1: Find the registration form
+forms = find(actual, Form(id="registration"))
+assert len(forms) == 1
+
+# Step 2: Validate the form structure
+registration_form = forms[0]
+expected_form = Form(
+    Input(name="email", type="email"),
+    Input(name="password", type="password"),
+    Button("Register", type="submit")
+)
+
+matches(registration_form, expected_form)
+```
+
+**Example: Testing multiple similar elements**
+
+```python
+from fasthtml.common import Div, Card
+
+actual = dashboard.render()
+
+# Find all cards
+cards = find(actual, Card())
+
+# Verify we have the right number
+assert len(cards) == 3
+
+# Validate each card has required structure
+for card in cards:
+    expected_card = Card(
+        Div(cls="card-header"),
+        Div(cls="card-body")
+    )
+    matches(card, expected_card)
+```
+
+### 6. Testing Edge Cases
+
+**Testing empty elements:**
+
+```python
+from myfasthtml.test.matcher import Empty, NoChildren
+from fasthtml.common import Div
+
+# Test completely empty element
+actual = Div()
+expected = Div(Empty())
+matches(actual, expected)
+
+# Test element with attributes but no children
+actual = Div(id="container", cls="empty-state")
+expected = Div(NoChildren())
+matches(actual, expected)
+```
+
+**Testing absence of elements:**
+
+```python
+from myfasthtml.test.matcher import find
+from fasthtml.common import Div
+
+actual = basic_view.render()
+
+# Verify admin section is not present
+try:
+    find(actual, Div(id="admin-section"))
+    assert False, "Admin section should not be present"
+except AssertionError as e:
+    if "No element found" in str(e):
+        pass  # Expected - admin section absent
+    else:
+        raise
+```
+
+---
+
+## Part 3: How It Works (Technical Overview)
+
+Understanding how the matcher works helps you write better tests and debug failures more effectively.
+
+### The Matching Algorithm
+
+When you call `matches(actual, expected)`, here's what happens:
+
+1. **Type Comparison**: Checks if elements have the same type/tag
+   - For FastHTML elements: compares `.tag` (e.g., "div", "button")
+   - For Python objects: compares class types
+
+2. **Attribute Validation**: For each attribute in `expected`:
+   - Checks if attribute exists in `actual`
+   - If it's a `Predicate`: calls `.validate(actual_value)`
+   - Otherwise: checks for exact equality
+   - **Key point**: Only attributes in `expected` are checked
+
+3. **Children Validation**:
+   - Applies `ChildrenPredicate` validators if present
+   - Recursively matches children in order
+   - **Key point**: Only checks as many children as defined in `expected`
+
+4. **Path Tracking**: Maintains a path through the tree for error reporting
+
+### Understanding the Path
+
+The matcher builds a path as it traverses your element tree:
+
+```
+div#container.form.input[name=email]
+```
+
+This path means:
+- Started at a `div` with `id="container"`
+- Went to a `form` element
+- Then to an `input` with `name="email"`
+
+The path appears in error messages to help you locate problems:
+
+```
+Path  : 'div#form.input[name=email]'
+Error : 'type' is not found in Actual
+```
+
+### How Predicates Work
+
+Predicates are objects that implement a `validate()` method:
+
+```python
+class Contains(AttrPredicate):
+    def validate(self, actual):
+        return self.value in actual
+```
+
+When matching encounters a predicate:
+1. Gets the actual attribute value
+2. Calls `predicate.validate(actual_value)`
+3. If returns `False`, reports validation error
+
+This allows flexible matching without hardcoding exact values.
+
+### Error Output Generation
+
+When a test fails, the matcher generates a side-by-side comparison:
+
+**Process:**
+1. Renders both `actual` and `expected` as tree structures
+2. Compares them element by element
+3. Marks differences with `^^^` characters
+4. Aligns output for easy visual comparison
+
+**Example:**
+```
+(div "id"="old"        | (div "id"="new"
+     ^^^^              |      
+```
+
+The `^^^` appears under attributes or content that don't match.
+
+### The find() Algorithm
+
+`find()` uses depth-first search:
+
+1. **Check current element**: Does it match the pattern?
+   - If yes: add to results
+
+2. **Search children**: Recursively search all children
+
+3. **Return all matches**: Collects matches from entire tree
+
+**Key difference from matches()**: `find()` looks for any occurrence anywhere in the tree, while `matches()` validates exact structure.
+
+---
+
+## Best Practices
+
+### Do's ✅
+
+**Test only what matters**
+```python
+# ✅ Good - tests only the submit action
+expected = Button("Submit", hx_post="/api/save")
+
+# ❌ Bad - tests irrelevant details
+expected = Button("Submit", hx_post="/api/save", id="btn-123", cls="btn btn-primary")
+```
+
+**Use predicates for dynamic values**
+```python
+# ✅ Good - flexible for generated IDs
+expected = Div(id=StartsWith("generated-"))
+
+# ❌ Bad - brittle, will break on regeneration
+expected = Div(id="generated-12345")
+```
+
+**Structure tests in layers**
+```python
+# ✅ Good - separate concerns
+# Test 1: Overall structure
+matches(page, Div(Header(), Main(), Footer()))
+
+# Test 2: Header details
+header = find(page, Header())[0]
+matches(header, Header(Nav(), Div(cls="user-menu")))
+
+# ❌ Bad - everything in one giant test
+matches(page, Div(
+    Header(Nav(...), Div(...)),
+    Main(...),
+    Footer(...)
+))
+```
+
+**Verify element counts with find()**
+```python
+# ✅ Good - explicit count check
+buttons = find(page, Button())
+assert len(buttons) == 3, f"Expected 3 buttons, found {len(buttons)}"
+
+# ❌ Bad - implicit assumption
+button = find(page, Button())[0]  # Fails if 0 or multiple buttons
+```
+
+### Don'ts ❌
+
+**Don't test implementation details**
+```python
+# ❌ Bad - internal div structure might change
+expected = Div(
+    Div(
+        Div(Button("Click"))
+    )
+)
+
+# ✅ Good - test the important element
+expected = Div(Button("Click"))
+```
+
+**Don't use exact string matching**
+```python
+# ❌ Bad - fragile
+assert str(component.render()) == '<div><p>Text</p></div>'
+
+# ✅ Good - structural matching
+matches(component.render(), Div(P("Text")))
+```
+
+**Don't over-specify**
+```python
+# ❌ Bad - tests too much
+expected = Form(
+    Input(name="email", type="email", id="email-input", cls="form-control"),
+    Input(name="password", type="password", id="pwd-input", cls="form-control"),
+    Button("Submit", type="submit", id="submit-btn", cls="btn btn-primary")
+)
+
+# ✅ Good - tests what matters
+expected = Form(
+    Input(name="email", type="email"),
+    Input(name="password", type="password"),
+    Button("Submit", type="submit")
+)
+```
+
+### Performance Tips
+
+**Reuse patterns**
+```python
+# Define reusable patterns
+STANDARD_BUTTON = Button(cls=Contains("btn"))
+
+# Use in multiple tests
+matches(actual, Div(STANDARD_BUTTON))
+```
+
+**Use find() efficiently**
+```python
+# ✅ Good - specific pattern
+buttons = find(page, Button(cls="primary"))
+
+# ❌ Inefficient - too broad then filter
+all_buttons = find(page, Button())
+primary = [b for b in all_buttons if "primary" in b.attrs.get("cls", "")]
+```
+
+---
+
+## Quick Reference
+
+### Import Statements
+
+```python
+# Core functions
+from myfasthtml.test.matcher import matches, find
+
+# AttrPredicates
+from myfasthtml.test.matcher import Contains, StartsWith, DoesNotContain, AnyValue
+
+# ChildrenPredicates
+from myfasthtml.test.matcher import Empty, NoChildren, AttributeForbidden
+
+# For custom test objects
+from myfasthtml.test.matcher import TestObject
+```
+
+### Common Patterns Cheatsheet
+
+```python
+# Basic validation
+matches(actual, expected)
+
+# Find and validate
+elements = find(tree, pattern)
+assert len(elements) == 1
+matches(elements[0], detailed_pattern)
+
+# Flexible attribute matching
+expected = Div(
+    id=StartsWith("prefix-"),
+    cls=Contains("active"),
+    data_value=AnyValue()
+)
+
+# Empty element validation
+expected = Div(Empty())          # No children, no attributes
+expected = Div(NoChildren())     # No children, attributes OK
+
+# Forbidden attribute
+expected = Button(AttributeForbidden("disabled"))
+
+# Multiple children
+expected = Div(
+    Header(),
+    Main(),
+    Footer()
+)
+```
+
+---
+
+## Conclusion
+
+The matcher module provides powerful tools for testing FastHTML components:
+
+- **`matches()`** validates structure with precise, readable error messages
+- **`find()`** locates elements anywhere in your HTML tree
+- **Predicates** enable flexible, maintainable tests
+
+By focusing on what matters and using the right patterns, you can write component tests that are both robust and easy to maintain.
+
+**Next steps:**
+- Practice with simple components first
+- Gradually introduce predicates as needed
+- Review error messages carefully - they guide you to the problem
+- Refactor tests to remove duplication
+
+Happy testing! 🧪

requirements.txt

@@ -38,7 +38,7 @@ mdurl==0.1.2
 more-itertools==10.8.0
 myauth==0.2.1
 mydbengine==0.1.0
-myutils==0.4.0
+myutils==0.5.0
 nh3==0.3.1
 numpy==2.3.5
 oauthlib==3.3.1

src/app.py

@@ -4,15 +4,18 @@ import yaml
 from fasthtml import serve
 
 from myfasthtml.controls.CommandsDebugger import CommandsDebugger
+from myfasthtml.controls.DataGridsManager import DataGridsManager
 from myfasthtml.controls.Dropdown import Dropdown
 from myfasthtml.controls.FileUpload import FileUpload
 from myfasthtml.controls.InstancesDebugger import InstancesDebugger
 from myfasthtml.controls.Keyboard import Keyboard
 from myfasthtml.controls.Layout import Layout
 from myfasthtml.controls.TabsManager import TabsManager
+from myfasthtml.controls.TreeView import TreeView, TreeNode
 from myfasthtml.controls.helpers import Ids, mk
 from myfasthtml.core.instances import UniqueInstance
 from myfasthtml.icons.carbon import volume_object_storage
+from myfasthtml.icons.fluent_p2 import key_command16_regular
 from myfasthtml.icons.fluent_p3 import folder_open20_regular
 from myfasthtml.myfastapp import create_app
 
@@ -31,11 +34,57 @@ app, rt = create_app(protect_routes=True,
                      base_url="http://localhost:5003")
 
 
+def create_sample_treeview(parent):
+  """
+  Create a sample TreeView with a file structure for testing.
+
+  Args:
+      parent: Parent instance for the TreeView
+
+  Returns:
+      TreeView: Configured TreeView instance with sample data
+  """
+  tree_view = TreeView(parent, _id="-treeview")
+  
+  # Create sample file structure
+  projects = TreeNode(label="Projects", type="folder")
+  tree_view.add_node(projects)
+  
+  myfasthtml = TreeNode(label="MyFastHtml", type="folder")
+  tree_view.add_node(myfasthtml, parent_id=projects.id)
+  
+  app_py = TreeNode(label="app.py", type="file")
+  tree_view.add_node(app_py, parent_id=myfasthtml.id)
+  
+  readme = TreeNode(label="README.md", type="file")
+  tree_view.add_node(readme, parent_id=myfasthtml.id)
+  
+  src_folder = TreeNode(label="src", type="folder")
+  tree_view.add_node(src_folder, parent_id=myfasthtml.id)
+  
+  controls_py = TreeNode(label="controls.py", type="file")
+  tree_view.add_node(controls_py, parent_id=src_folder.id)
+  
+  documents = TreeNode(label="Documents", type="folder")
+  tree_view.add_node(documents, parent_id=projects.id)
+  
+  notes = TreeNode(label="notes.txt", type="file")
+  tree_view.add_node(notes, parent_id=documents.id)
+  
+  todo = TreeNode(label="todo.md", type="file")
+  tree_view.add_node(todo, parent_id=documents.id)
+  
+  # Expand all nodes to show the full structure
+  # tree_view.expand_all()
+  
+  return tree_view
+
+
 @rt("/")
 def index(session):
   session_instance = UniqueInstance(session=session, _id=Ids.UserSession)
   layout = Layout(session_instance, "Testing Layout")
-  layout.set_footer("Goodbye World")
+  layout.footer_left.add("Goodbye World")
   
   tabs_manager = TabsManager(layout, _id=f"-tabs_manager")
   add_tab = tabs_manager.commands.add_tab
@@ -51,7 +100,7 @@ def index(session):
   
   commands_debugger = CommandsDebugger(layout)
   btn_show_commands_debugger = mk.label("Commands",
-                                        icon=None,
+                                        icon=key_command16_regular,
                                         command=add_tab("Commands", commands_debugger),
                                         id=commands_debugger.get_id())
   
@@ -63,12 +112,17 @@ def index(session):
   btn_popup = mk.label("Popup",
                        command=add_tab("Popup", Dropdown(layout, "Content", button="button", _id="-dropdown")))
   
+  # Create TreeView with sample data
+  tree_view = create_sample_treeview(layout)
+  
   layout.header_left.add(tabs_manager.add_tab_btn())
   layout.header_right.add(btn_show_right_drawer)
   layout.left_drawer.add(btn_show_instances_debugger, "Debugger")
   layout.left_drawer.add(btn_show_commands_debugger, "Debugger")
   layout.left_drawer.add(btn_file_upload, "Test")
   layout.left_drawer.add(btn_popup, "Test")
+  layout.left_drawer.add(tree_view, "TreeView")
+  layout.left_drawer.add(DataGridsManager(layout, _id="-datagrids"), "Documents")
   layout.set_main(tabs_manager)
   keyboard = Keyboard(layout, _id="-keyboard").add("ctrl+o",
                                                    add_tab("File Open", FileUpload(layout, _id="-file_upload")))

src/myfasthtml/assets/myfasthtml.css

@@ -3,6 +3,7 @@
     --font-sans: ui-sans-serif, system-ui, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Noto Color Emoji';
     --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', monospace;
     --spacing: 0.25rem;
+    --text-xs: 0.6875rem;
     --text-sm: 0.875rem;
     --text-sm--line-height: calc(1.25 / 0.875);
     --text-xl: 1.25rem;
@@ -11,6 +12,8 @@
     --radius-md: 0.375rem;
     --default-font-family: var(--font-sans);
     --default-mono-font-family: var(--font-mono);
+    --properties-font-size: var(--text-xs);
+    --mf-tooltip-zindex: 10;
 }
 
 
@@ -56,6 +59,26 @@
  * Compatible with DaisyUI 5
  */
 
+.mf-tooltip-container {
+    background: var(--color-base-200);
+    padding: 5px 10px;
+    border-radius: 4px;
+    pointer-events: none; /* Prevent interfering with mouse events */
+    font-size: 12px;
+    white-space: nowrap;
+    opacity: 0; /* Default to invisible */
+    visibility: hidden; /* Prevent interaction when invisible */
+    transition: opacity 0.3s ease, visibility 0s linear 0.3s; /* Delay visibility removal */
+    position: fixed; /* Keep it above other content and adjust position */
+    z-index: var(--mf-tooltip-zindex); /* Ensure it's on top */
+}
+
+.mf-tooltip-container[data-visible="true"] {
+    opacity: 1;
+    visibility: visible; /* Show tooltip */
+    transition: opacity 0.3s ease; /* No delay when becoming visible */
+}
+
 /* Main layout container using CSS Grid */
 .mf-layout {
     display: grid;
@@ -465,4 +488,281 @@
 .mf-dropdown.is-visible {
     display: block;
     opacity: 1;
+}
+
+/* *********************************************** */
+/* ************** TreeView Component ************* */
+/* *********************************************** */
+
+/* TreeView Container */
+.mf-treeview {
+    width: 100%;
+    user-select: none;
+}
+
+/* TreeNode Container */
+.mf-treenode-container {
+    width: 100%;
+}
+
+/* TreeNode Element */
+.mf-treenode {
+    display: flex;
+    align-items: center;
+    gap: 0.25rem;
+    padding: 2px 0.5rem;
+    cursor: pointer;
+    transition: background-color 0.15s ease;
+    border-radius: 0.25rem;
+}
+
+/* Input for Editing */
+.mf-treenode-input {
+    flex: 1;
+    padding: 2px 0.25rem;
+    border: 1px solid var(--color-primary);
+    border-radius: 0.25rem;
+    background-color: var(--color-base-100);
+    outline: none;
+}
+
+
+.mf-treenode:hover {
+    background-color: var(--color-base-200);
+}
+
+.mf-treenode.selected {
+    background-color: var(--color-primary);
+    color: var(--color-primary-content);
+}
+
+/* Toggle Icon */
+.mf-treenode-toggle {
+    flex-shrink: 0;
+    width: 20px;
+    text-align: center;
+    font-size: 0.75rem;
+}
+
+/* Node Label */
+.mf-treenode-label {
+    flex: 1;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+}
+
+
+.mf-treenode-input:focus {
+    box-shadow: 0 0 0 2px color-mix(in oklab, var(--color-primary) 25%, transparent);
+}
+
+/* Action Buttons - Hidden by default, shown on hover */
+.mf-treenode-actions {
+    display: none;
+    gap: 0.1rem;
+    white-space: nowrap;
+    margin-left: 0.5rem;
+}
+
+.mf-treenode:hover .mf-treenode-actions {
+    display: flex;
+}
+
+/* *********************************************** */
+/* ********** Generic Resizer Classes ************ */
+/* *********************************************** */
+
+/* Generic resizer - used by both Layout and Panel */
+.mf-resizer {
+    position: absolute;
+    width: 4px;
+    cursor: col-resize;
+    background-color: transparent;
+    transition: background-color 0.2s ease;
+    z-index: 100;
+    top: 0;
+    bottom: 0;
+}
+
+.mf-resizer:hover {
+    background-color: rgba(59, 130, 246, 0.3);
+}
+
+/* Active state during resize */
+.mf-resizing .mf-resizer {
+    background-color: rgba(59, 130, 246, 0.5);
+}
+
+/* Prevent text selection during resize */
+.mf-resizing {
+    user-select: none;
+    -webkit-user-select: none;
+    -moz-user-select: none;
+    -ms-user-select: none;
+}
+
+/* Cursor override for entire body during resize */
+.mf-resizing * {
+    cursor: col-resize !important;
+}
+
+/* Visual indicator for resizer on hover - subtle border */
+.mf-resizer::before {
+    content: '';
+    position: absolute;
+    top: 50%;
+    transform: translateY(-50%);
+    width: 2px;
+    height: 40px;
+    background-color: rgba(156, 163, 175, 0.4);
+    border-radius: 2px;
+    opacity: 0;
+    transition: opacity 0.2s ease;
+}
+
+.mf-resizer:hover::before,
+.mf-resizing .mf-resizer::before {
+    opacity: 1;
+}
+
+/* Resizer positioning */
+/* Left resizer is on the right side of the left panel */
+.mf-resizer-left {
+    right: 0;
+}
+
+/* Right resizer is on the left side of the right panel */
+.mf-resizer-right {
+    left: 0;
+}
+
+/* Position indicator for resizer */
+.mf-resizer-left::before {
+    right: 1px;
+}
+
+.mf-resizer-right::before {
+    left: 1px;
+}
+
+/* Disable transitions during resize for smooth dragging */
+.mf-item-resizing {
+    transition: none !important;
+}
+
+/* *********************************************** */
+/* *************** Panel Component *************** */
+/* *********************************************** */
+
+.mf-panel {
+    display: flex;
+    width: 100%;
+    height: 100%;
+    overflow: hidden;
+    position: relative;
+}
+
+.mf-panel-left {
+    position: relative;
+    flex-shrink: 0;
+    width: 250px;
+    min-width: 150px;
+    max-width: 400px;
+    height: 100%;
+    overflow: auto;
+    border-right: 1px solid var(--color-border-primary);
+}
+
+.mf-panel-main {
+    flex: 1;
+    height: 100%;
+    overflow: auto;
+    min-width: 0; /* Important to allow the shrinking of flexbox */
+}
+
+.mf-panel-right {
+    position: relative;
+    flex-shrink: 0;
+    width: 300px;
+    min-width: 150px;
+    max-width: 500px;
+    height: 100%;
+    overflow: auto;
+    border-left: 1px solid var(--color-border-primary);
+    padding: 0.5rem;
+}
+
+/* *********************************************** */
+/* ************* Properties Component ************ */
+/* *********************************************** */
+
+/* Properties container */
+.mf-properties {
+    display: flex;
+    flex-direction: column;
+    gap: 1rem;
+}
+
+/* Group card - using DaisyUI card styling */
+.mf-properties-group-card {
+    background-color: var(--color-base-100);
+    border: 1px solid color-mix(in oklab, var(--color-base-content) 10%, transparent);
+    border-radius: var(--radius-md);
+    overflow: hidden;
+    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
+}
+
+/* Group header - gradient using DaisyUI primary color */
+.mf-properties-group-header {
+    background: linear-gradient(135deg, var(--color-primary) 0%, color-mix(in oklab, var(--color-primary) 80%, black) 100%);
+    color: var(--color-primary-content);
+    padding: calc(var(--properties-font-size) * 0.5) calc(var(--properties-font-size) * 0.75);
+    font-weight: 700;
+    font-size: var(--properties-font-size);
+}
+
+/* Group content area */
+.mf-properties-group-content {
+    display: flex;
+    flex-direction: column;
+}
+
+/* Property row */
+.mf-properties-row {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: calc(var(--properties-font-size) * 0.4) calc(var(--properties-font-size) * 0.75);
+    border-bottom: 1px solid color-mix(in oklab, var(--color-base-content) 5%, transparent);
+    transition: background-color 0.15s ease;
+    gap: calc(var(--properties-font-size) * 0.75);
+}
+
+.mf-properties-row:last-child {
+    border-bottom: none;
+}
+
+.mf-properties-row:hover {
+    background-color: color-mix(in oklab, var(--color-base-content) 3%, transparent);
+}
+
+/* Property key - normal font */
+.mf-properties-key {
+    font-weight: 600;
+    color: color-mix(in oklab, var(--color-base-content) 70%, transparent);
+    flex: 0 0 40%;
+    font-size: var(--properties-font-size);
+}
+
+/* Property value - monospace font */
+.mf-properties-value {
+    font-family: var(--default-mono-font-family);
+    color: var(--color-base-content);
+    flex: 1;
+    text-align: right;
+    font-size: var(--properties-font-size);
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
 }

src/myfasthtml/assets/myfasthtml.js

@@ -1,40 +1,43 @@
 /**
- * Layout Drawer Resizer
+ * Generic Resizer
  *
- * Handles resizing of left and right drawers with drag functionality.
+ * Handles resizing of elements with drag functionality.
  * Communicates with server via HTMX to persist width changes.
+ * Works for both Layout drawers and Panel sides.
  */
 
 /**
- * Initialize drawer resizer functionality for a specific layout instance
+ * Initialize resizer functionality for a specific container
  *
- * @param {string} layoutId - The ID of the layout instance to initialize
+ * @param {string} containerId - The ID of the container instance to initialize
+ * @param {Object} options - Configuration options
+ * @param {number} options.minWidth - Minimum width in pixels (default: 150)
+ * @param {number} options.maxWidth - Maximum width in pixels (default: 600)
  */
-function initLayoutResizer(layoutId) {
-  'use strict';
+function initResizer(containerId, options = {}) {
 
-  const MIN_WIDTH = 150;
-  const MAX_WIDTH = 600;
+  const MIN_WIDTH = options.minWidth || 150;
+  const MAX_WIDTH = options.maxWidth || 600;
 
   let isResizing = false;
   let currentResizer = null;
-  let currentDrawer = null;
+  let currentItem = null;
   let startX = 0;
   let startWidth = 0;
   let side = null;
 
-  const layoutElement = document.getElementById(layoutId);
+  const containerElement = document.getElementById(containerId);
 
-  if (!layoutElement) {
-    console.error(`Layout element with ID "${layoutId}" not found`);
+  if (!containerElement) {
+    console.error(`Container element with ID "${containerId}" not found`);
     return;
   }
 
   /**
-   * Initialize resizer functionality for this layout instance
+   * Initialize resizer functionality for this container instance
    */
   function initResizers() {
-    const resizers = layoutElement.querySelectorAll('.mf-layout-resizer');
+    const resizers = containerElement.querySelectorAll('.mf-resizer');
 
     resizers.forEach(resizer => {
       // Remove existing listener if any to avoid duplicates
@@ -51,24 +54,24 @@ function initLayoutResizer(layoutId) {
 
     currentResizer = e.target;
     side = currentResizer.dataset.side;
-    currentDrawer = currentResizer.closest('.mf-layout-drawer');
+    currentItem = currentResizer.parentElement;
 
-    if (!currentDrawer) {
-      console.error('Could not find drawer element');
+    if (!currentItem) {
+      console.error('Could not find item element');
       return;
     }
 
     isResizing = true;
     startX = e.clientX;
-    startWidth = currentDrawer.offsetWidth;
+    startWidth = currentItem.offsetWidth;
 
     // Add event listeners for mouse move and up
     document.addEventListener('mousemove', handleMouseMove);
     document.addEventListener('mouseup', handleMouseUp);
 
     // Add resizing class for visual feedback
-    document.body.classList.add('mf-layout-resizing');
-    currentDrawer.classList.add('mf-layout-drawer-resizing');
+    document.body.classList.add('mf-resizing');
+    currentItem.classList.add('mf-item-resizing');
   }
 
   /**
@@ -92,8 +95,8 @@ function initLayoutResizer(layoutId) {
     // Constrain width between min and max
     newWidth = Math.max(MIN_WIDTH, Math.min(MAX_WIDTH, newWidth));
 
-    // Update drawer width visually
-    currentDrawer.style.width = `${newWidth}px`;
+    // Update item width visually
+    currentItem.style.width = `${newWidth}px`;
   }
 
   /**
@@ -109,11 +112,11 @@ function initLayoutResizer(layoutId) {
     document.removeEventListener('mouseup', handleMouseUp);
 
     // Remove resizing classes
-    document.body.classList.remove('mf-layout-resizing');
-    currentDrawer.classList.remove('mf-layout-drawer-resizing');
+    document.body.classList.remove('mf-resizing');
+    currentItem.classList.remove('mf-item-resizing');
 
     // Get final width
-    const finalWidth = currentDrawer.offsetWidth;
+    const finalWidth = currentItem.offsetWidth;
     const commandId = currentResizer.dataset.commandId;
 
     if (!commandId) {
@@ -122,24 +125,24 @@ function initLayoutResizer(layoutId) {
     }
 
     // Send width update to server
-    saveDrawerWidth(commandId, finalWidth);
+    saveWidth(commandId, finalWidth);
 
     // Reset state
     currentResizer = null;
-    currentDrawer = null;
+    currentItem = null;
     side = null;
   }
 
   /**
-   * Save drawer width to server via HTMX
+   * Save width to server via HTMX
    */
-  function saveDrawerWidth(commandId, width) {
+  function saveWidth(commandId, width) {
     htmx.ajax('POST', '/myfasthtml/commands', {
       headers: {
         "Content-Type": "application/x-www-form-urlencoded"
       },
       swap: "outerHTML",
-      target: `#${currentDrawer.id}`,
+      target: `#${currentItem.id}`,
       values: {
         c_id: commandId,
         width: width
@@ -150,12 +153,119 @@ function initLayoutResizer(layoutId) {
   // Initialize resizers
   initResizers();
 
-  // Re-initialize after HTMX swaps within this layout
-  layoutElement.addEventListener('htmx:afterSwap', function (event) {
+  // Re-initialize after HTMX swaps within this container
+  containerElement.addEventListener('htmx:afterSwap', function (event) {
     initResizers();
   });
 }
 
+function bindTooltipsWithDelegation(elementId) {
+  // To display the tooltip, the attribute 'data-tooltip' is mandatory => it contains the text to tooltip
+  // Then
+  //      the 'truncate' to show only when the text is truncated
+  //      the class 'mmt-tooltip' for force the display
+
+  console.info("bindTooltips on element " + elementId);
+
+  const element = document.getElementById(elementId);
+  const tooltipContainer = document.getElementById(`tt_${elementId}`);
+
+
+  if (!element) {
+    console.error(`Invalid element '${elementId}' container`);
+    return;
+  }
+
+  if (!tooltipContainer) {
+    console.error(`Invalid tooltip 'tt_${elementId}' container.`);
+    return;
+  }
+
+  // Add a single mouseenter and mouseleave listener to the parent element
+  element.addEventListener("mouseenter", (event) => {
+    //console.debug("Entering element", event.target)
+
+    const cell = event.target.closest("[data-tooltip]");
+    if (!cell) {
+      // console.debug("  No 'data-tooltip' attribute found. Stopping.");
+      return;
+    }
+
+    const no_tooltip = element.hasAttribute("mf-no-tooltip");
+    if (no_tooltip) {
+      // console.debug("  Attribute 'mmt-no-tooltip' found. Cancelling.");
+      return;
+    }
+
+    const content = cell.querySelector(".truncate") || cell;
+    const isOverflowing = content.scrollWidth > content.clientWidth;
+    const forceShow = cell.classList.contains("mf-tooltip");
+
+    if (isOverflowing || forceShow) {
+      const tooltipText = cell.getAttribute("data-tooltip");
+      if (tooltipText) {
+        const rect = cell.getBoundingClientRect();
+        const tooltipRect = tooltipContainer.getBoundingClientRect();
+
+        let top = rect.top - 30; // Above the cell
+        let left = rect.left;
+
+        // Adjust tooltip position to prevent it from going off-screen
+        if (top < 0) top = rect.bottom + 5; // Move below if no space above
+        if (left + tooltipRect.width > window.innerWidth) {
+          left = window.innerWidth - tooltipRect.width - 5; // Prevent overflow right
+        }
+
+        // Apply styles for tooltip positioning
+        requestAnimationFrame(() => {
+          tooltipContainer.textContent = tooltipText;
+          tooltipContainer.setAttribute("data-visible", "true");
+          tooltipContainer.style.top = `${top}px`;
+          tooltipContainer.style.left = `${left}px`;
+        });
+      }
+    }
+  }, true); // Use capture phase for better delegation if needed
+
+  element.addEventListener("mouseleave", (event) => {
+    const cell = event.target.closest("[data-tooltip]");
+    if (cell) {
+      tooltipContainer.setAttribute("data-visible", "false");
+    }
+  }, true); // Use capture phase for better delegation if needed
+}
+
+function initLayout(elementId) {
+  initResizer(elementId);
+  bindTooltipsWithDelegation(elementId);
+}
+
+function disableTooltip() {
+  const elementId = tooltipElementId
+  // console.debug("disableTooltip on element " + elementId);
+
+  const element = document.getElementById(elementId);
+  if (!element) {
+    console.error(`Invalid element '${elementId}' container`);
+    return;
+  }
+
+  element.setAttribute("mmt-no-tooltip", "");
+}
+
+function enableTooltip() {
+  const elementId = tooltipElementId
+  // console.debug("enableTooltip on element " + elementId);
+
+  const element = document.getElementById(elementId);
+  if (!element) {
+    console.error(`Invalid element '${elementId}' container`);
+    return;
+  }
+
+  element.removeAttribute("mmt-no-tooltip");
+}
+
 function initBoundaries(elementId, updateUrl) {
   function updateBoundaries() {
     const container = document.getElementById(elementId);
@@ -360,7 +470,6 @@ function updateTabs(controllerId) {
 
     for (const [combinationStr, config] of Object.entries(combinations)) {
       const sequence = parseCombination(combinationStr);
-      console.log("Parsing combination", combinationStr, "=>", sequence);
       let currentNode = root;
 
       for (const keySet of sequence) {
@@ -1351,4 +1460,5 @@ function updateTabs(controllerId) {
       detachGlobalListener();
     }
   };
-})();
+})();
+

src/myfasthtml/controls/CommandsDebugger.py

@@ -5,6 +5,10 @@ from myfasthtml.core.network_utils import from_parent_child_list
 
 
 class CommandsDebugger(SingleInstance):
+  """
+  Represents a debugger designed for visualizing and managing commands in a parent-child
+  hierarchical structure.
+  """
   def __init__(self, parent, _id=None):
     super().__init__(parent, _id=_id)
   

src/myfasthtml/controls/DataGrid.py

@@ -0,0 +1,59 @@
+from typing import Optional
+
+from fasthtml.components import Div
+
+from myfasthtml.controls.BaseCommands import BaseCommands
+from myfasthtml.controls.datagrid_objects import DataGridColumnState, DataGridRowState, DataGridFooterConf, \
+  DatagridSelectionState, DataGridHeaderFooterConf, DatagridEditionState
+from myfasthtml.core.dbmanager import DbObject
+from myfasthtml.core.instances import MultipleInstance
+
+
+class DatagridState(DbObject):
+  def __init__(self, owner):
+    super().__init__(owner)
+    with self.initializing():
+      self.sidebar_visible: bool = False
+      self.selected_view: str = None
+      self.row_index: bool = False
+      self.columns: list[DataGridColumnState] = []
+      self.rows: list[DataGridRowState] = []  # only the rows that have a specific state
+      self.headers: list[DataGridHeaderFooterConf] = []
+      self.footers: list[DataGridHeaderFooterConf] = []
+      self.sorted: list = []
+      self.filtered: dict = {}
+      self.edition: DatagridEditionState = DatagridEditionState()
+      self.selection: DatagridSelectionState = DatagridSelectionState()
+
+
+class DatagridSettings(DbObject):
+  def __init__(self, owner):
+    super().__init__(owner)
+    with self.initializing():
+      self.file_name: Optional[str] = None
+      self.selected_sheet_name: Optional[str] = None
+      self.header_visible: bool = True
+      self.filter_all_visible: bool = True
+      self.views_visible: bool = True
+      self.open_file_visible: bool = True
+      self.open_settings_visible: bool = True
+
+
+class Commands(BaseCommands):
+  pass
+
+
+class DataGrid(MultipleInstance):
+  def __init__(self, parent, settings=None, _id=None):
+    super().__init__(parent, _id=_id)
+    self._settings = DatagridSettings(self).update(settings)
+    self._state = DatagridState(self)
+    self.commands = Commands(self)
+  
+  def render(self):
+    return Div(
+      self._id
+    )
+  
+  def __ft__(self):
+    return self.render()

src/myfasthtml/controls/DataGridsManager.py

@@ -0,0 +1,58 @@
+import pandas as pd
+from fasthtml.components import Div
+
+from myfasthtml.controls.BaseCommands import BaseCommands
+from myfasthtml.controls.TabsManager import TabsManager
+from myfasthtml.controls.TreeView import TreeView
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+from myfasthtml.core.instances import MultipleInstance, InstancesManager
+from myfasthtml.icons.fluent_p1 import table_add20_regular
+from myfasthtml.icons.fluent_p3 import folder_open20_regular
+
+
+class Commands(BaseCommands):
+  def upload_from_source(self):
+    return Command("UploadFromSource", "Upload from source", self._owner.upload_from_source)
+  
+  def new_grid(self):
+    return Command("NewGrid", "New grid", self._owner.new_grid)
+  
+  def open_from_excel(self, tab_id, get_content_callback):
+    excel_content = get_content_callback()
+    return Command("OpenFromExcel", "Open from Excel", self._owner.open_from_excel, tab_id, excel_content)
+
+
+class DataGridsManager(MultipleInstance):
+  def __init__(self, parent, _id=None):
+    super().__init__(parent, _id=_id)
+    self.tree = TreeView(self, _id="-treeview")
+    self.commands = Commands(self)
+    self._tabs_manager = InstancesManager.get_by_type(self._session, TabsManager)
+  
+  def upload_from_source(self):
+    from myfasthtml.controls.FileUpload import FileUpload
+    file_upload = FileUpload(self, _id="-file-upload", auto_register=False)
+    self._tabs_manager = InstancesManager.get_by_type(self._session, TabsManager)
+    tab_id = self._tabs_manager.add_tab("Upload Datagrid", file_upload)
+    file_upload.on_ok = self.commands.open_from_excel(tab_id, file_upload.get_content)
+    return self._tabs_manager.show_tab(tab_id)
+  
+  def open_from_excel(self, tab_id, excel_content):
+    df = pd.read_excel(excel_content)
+    content = df.to_html(index=False)
+    self._tabs_manager.switch(tab_id, content)
+  
+  def render(self):
+    return Div(
+      Div(
+        mk.icon(folder_open20_regular, tooltip="Upload from source", command=self.commands.upload_from_source()),
+        mk.icon(table_add20_regular, tooltip="New grid"),
+        cls="flex"
+      ),
+      self.tree,
+      id=self._id,
+    )
+  
+  def __ft__(self):
+    return self.render()

src/myfasthtml/controls/Dropdown.py

@@ -22,13 +22,18 @@ class DropdownState:
 
 
 class Dropdown(MultipleInstance):
+  """
+  Represents a dropdown component that can be toggled open or closed. This class is used
+  to create interactive dropdown elements, allowing for container and button customization.
+  The dropdown provides functionality to manage its state, including opening, closing, and
+  handling user interactions.
+  """
   def __init__(self, parent, content=None, button=None, _id=None):
     super().__init__(parent, _id=_id)
     self.button = Div(button) if not isinstance(button, FT) else button
     self.content = content
     self.commands = Commands(self)
     self._state = DropdownState()
-    self._toggle_command = self.commands.toggle()
   
   def toggle(self):
     self._state.opened = not self._state.opened
@@ -55,7 +60,7 @@ class Dropdown(MultipleInstance):
         self._mk_content(),
         cls="mf-dropdown-wrapper"
       ),
-      Keyboard(self, "-keyboard").add("esc", self.commands.close()),
+      Keyboard(self, _id="-keyboard").add("esc", self.commands.close()),
       Mouse(self, "-mouse").add("click", self.commands.click()),
       id=self._id
     )

src/myfasthtml/controls/FileUpload.py

@@ -6,7 +6,7 @@ from fastapi import UploadFile
 from fasthtml.components import *
 
 from myfasthtml.controls.BaseCommands import BaseCommands
-from myfasthtml.controls.helpers import Ids, mk
+from myfasthtml.controls.helpers import mk
 from myfasthtml.core.commands import Command
 from myfasthtml.core.dbmanager import DbObject
 from myfasthtml.core.instances import MultipleInstance
@@ -24,6 +24,7 @@ class FileUploadState(DbObject):
       self.ns_file_name: str | None = None
       self.ns_sheets_names: list | None = None
       self.ns_selected_sheet_name: str | None = None
+      self.ns_file_content: bytes | None = None
 
 
 class Commands(BaseCommands):
@@ -35,17 +36,25 @@ class Commands(BaseCommands):
 
 
 class FileUpload(MultipleInstance):
+  """
+  Represents a file upload component.
+
+  This class provides functionality to handle the uploading process of a file,
+  extract sheet names from an Excel file, and enables users to select a specific
+  sheet for further processing. It integrates commands and state management
+  to ensure smooth operation within a parent application.
+  """
   
-  def __init__(self, parent, _id=None):
-    super().__init__(parent, _id=_id)
+  def __init__(self, parent, _id=None, **kwargs):
+    super().__init__(parent, _id=_id, **kwargs)
     self.commands = Commands(self)
     self._state = FileUploadState(self)
   
   def upload_file(self, file: UploadFile):
     logger.debug(f"upload_file: {file=}")
     if file:
-      file_content = file.file.read()
-      self._state.ns_sheets_names = self.get_sheets_names(file_content)
+      self._state.ns_file_content = file.file.read()
+      self._state.ns_sheets_names = self.get_sheets_names(self._state.ns_file_content)
       self._state.ns_selected_sheet_name = self._state.ns_sheets_names[0] if len(self._state.ns_sheets_names) > 0 else 0
     
     return self.mk_sheet_selector()
@@ -64,6 +73,10 @@ class FileUpload(MultipleInstance):
       cls="select select-bordered select-sm w-full ml-2"
     )
   
+  def get_content(self):
+    return self._state.ns_file_content
+    
+  
   @staticmethod
   def get_sheets_names(file_content):
     try:

src/myfasthtml/controls/InstancesDebugger.py

@@ -1,4 +1,7 @@
+from myfasthtml.controls.Panel import Panel
+from myfasthtml.controls.Properties import Properties
 from myfasthtml.controls.VisNetwork import VisNetwork
+from myfasthtml.core.commands import Command
 from myfasthtml.core.instances import SingleInstance, InstancesManager
 from myfasthtml.core.network_utils import from_parent_child_list
 
@@ -6,9 +9,28 @@ from myfasthtml.core.network_utils import from_parent_child_list
 class InstancesDebugger(SingleInstance):
   def __init__(self, parent, _id=None):
     super().__init__(parent, _id=_id)
+    self._panel = Panel(self, _id="-panel")
+    self._command = Command("ShowInstance",
+                            "Display selected Instance",
+                            self.on_network_event).htmx(target=f"#{self._panel.get_id()}_r")
   
   def render(self):
-    s_name = InstancesManager.get_session_user_name
+    nodes, edges = self._get_nodes_and_edges()
+    vis_network = VisNetwork(self, nodes=nodes, edges=edges, _id="-vis", events_handlers={"select_node": self._command})
+    return self._panel.set_main(vis_network)
+  
+  def on_network_event(self, event_data: dict):
+    session, instance_id = event_data["nodes"][0].split("#")
+    properties_def = {"Main": {"Id": "_id", "Parent Id": "_parent._id"},
+                      "State": {"_name": "_state._name", "*": "_state"},
+                      "Commands": {"*": "commands"},
+                      }
+    return self._panel.set_right(Properties(self,
+                                            InstancesManager.get(session, instance_id),
+                                            properties_def,
+                                            _id="-properties"))
+  
+  def _get_nodes_and_edges(self):
     instances = self._get_instances()
     nodes, edges = from_parent_child_list(
       instances,
@@ -23,9 +45,7 @@ class InstancesDebugger(SingleInstance):
     for node in nodes:
       node["shape"] = "box"
     
-    vis_network = VisNetwork(self, nodes=nodes, edges=edges, _id="-vis")
-    # vis_network.add_to_options(physics={"wind": {"x": 0, "y": 1}})
-    return vis_network
+    return nodes, edges
   
   def _get_instances(self):
     return list(InstancesManager.instances.values())

src/myfasthtml/controls/Keyboard.py

@@ -7,7 +7,13 @@ from myfasthtml.core.instances import MultipleInstance
 
 
 class Keyboard(MultipleInstance):
-  def __init__(self, parent, _id=None, combinations=None):
+  """
+  Represents a keyboard with customizable key combinations support.
+
+  The Keyboard class allows managing key combinations and their corresponding
+  actions for a given parent object.
+  """
+  def __init__(self, parent, combinations=None, _id=None):
     super().__init__(parent, _id=_id)
     self.combinations = combinations or {}
   

src/myfasthtml/controls/Layout.py

@@ -17,15 +17,17 @@ from myfasthtml.core.commands import Command
 from myfasthtml.core.dbmanager import DbObject
 from myfasthtml.core.instances import SingleInstance
 from myfasthtml.core.utils import get_id
-from myfasthtml.icons.fluent import panel_left_expand20_regular as left_drawer_icon
-from myfasthtml.icons.fluent_p2 import panel_right_expand20_regular as right_drawer_icon
+from myfasthtml.icons.fluent import panel_left_contract20_regular as left_drawer_contract
+from myfasthtml.icons.fluent import panel_left_expand20_regular as left_drawer_expand
+from myfasthtml.icons.fluent_p1 import panel_right_contract20_regular as right_drawer_contract
+from myfasthtml.icons.fluent_p2 import panel_right_expand20_regular as right_drawer_expand
 
 logger = logging.getLogger("LayoutControl")
 
 
 class LayoutState(DbObject):
-  def __init__(self, owner):
-    super().__init__(owner)
+  def __init__(self, owner, name=None):
+    super().__init__(owner, name=name)
     with self.initializing():
       self.left_drawer_open: bool = True
       self.right_drawer_open: bool = True
@@ -37,12 +39,13 @@ class Commands(BaseCommands):
   def toggle_drawer(self, side: Literal["left", "right"]):
     return Command("ToggleDrawer", f"Toggle {side} layout drawer", self._owner.toggle_drawer, side)
   
-  def update_drawer_width(self, side: Literal["left", "right"]):
+  def update_drawer_width(self, side: Literal["left", "right"], width: int = None):
     """
     Create a command to update drawer width.
     
     Args:
         side: Which drawer to update ("left" or "right")
+        width: New width in pixels. Given by the HTMX request
     
     Returns:
         Command: Command object for updating drawer width
@@ -114,7 +117,7 @@ class Layout(SingleInstance):
     
     # Content storage
     self._main_content = None
-    self._state = LayoutState(self)
+    self._state = LayoutState(self, "default_layout")
     self._boundaries = Boundaries(self)
     self.commands = Commands(self)
     self.left_drawer = self.Content(self)
@@ -124,15 +127,6 @@ class Layout(SingleInstance):
     self.footer_left = self.Content(self)
     self.footer_right = self.Content(self)
   
-  def set_footer(self, content):
-    """
-    Set the footer content.
-
-    Args:
-        content: FastHTML component(s) or content for the footer
-    """
-    self._footer_content = content
-  
   def set_main(self, content):
     """
     Set the main content area.
@@ -141,8 +135,21 @@ class Layout(SingleInstance):
         content: FastHTML component(s) or content for the main area
     """
     self._main_content = content
+    return self
   
   def toggle_drawer(self, side: Literal["left", "right"]):
+    """
+    Toggle the state of a drawer (open or close) based on the specified side. This
+    method also generates the corresponding icon and drawer elements for the
+    selected side.
+
+    :param side: The side of the drawer to toggle. Must be either "left" or "right".
+    :type side: Literal["left", "right"]
+    :return: A tuple containing the updated drawer icon and drawer elements for
+             the specified side.
+    :rtype: Tuple[Any, Any]
+    :raises ValueError: If the provided `side` is not "left" or "right".
+    """
     logger.debug(f"Toggle drawer: {side=}, {self._state.left_drawer_open=}")
     if side == "left":
       self._state.left_drawer_open = not self._state.left_drawer_open
@@ -188,15 +195,17 @@ class Layout(SingleInstance):
     return Header(
       Div(  # left
         self._mk_left_drawer_icon(),
-        *self.header_left.get_content(),
-        cls="flex gap-1"
+        *self._mk_content_wrapper(self.header_left, horizontal=True, show_group_name=False).children,
+        cls="flex gap-1",
+        id=f"{self._id}_hl"
       ),
       Div(  # right
-        *self.header_right.get_content()[None],
+        *self._mk_content_wrapper(self.header_right, horizontal=True, show_group_name=False).children,
         UserProfile(self),
-        cls="flex gap-1"
+        cls="flex gap-1",
+        id=f"{self._id}_hr"
       ),
-      cls="mf-layout-header"
+      cls="mf-layout-header",
     )
   
   def _mk_footer(self):
@@ -206,9 +215,17 @@ class Layout(SingleInstance):
     Returns:
         Footer: FastHTML Footer component
     """
-    footer_content = self._footer_content if self._footer_content else ""
     return Footer(
-      footer_content,
+      Div(  # left
+        *self._mk_content_wrapper(self.footer_left, horizontal=True, show_group_name=False).children,
+        cls="flex gap-1",
+        id=f"{self._id}_fl"
+      ),
+      Div(  # right
+        *self._mk_content_wrapper(self.footer_right, horizontal=True, show_group_name=False).children,
+        cls="flex gap-1",
+        id=f"{self._id}_fr"
+      ),
       cls="mf-layout-footer footer sm:footer-horizontal"
     )
   
@@ -233,7 +250,7 @@ class Layout(SingleInstance):
         Div: FastHTML Div component for left drawer
     """
     resizer = Div(
-      cls="mf-layout-resizer mf-layout-resizer-right",
+      cls="mf-resizer mf-resizer-left",
       data_command_id=self.commands.update_drawer_width("left").id,
       data_side="left"
     )
@@ -266,15 +283,23 @@ class Layout(SingleInstance):
     Returns:
         Div: FastHTML Div component for right drawer
     """
+    
     resizer = Div(
-      cls="mf-layout-resizer mf-layout-resizer-left",
+      cls="mf-resizer mf-resizer-right",
       data_command_id=self.commands.update_drawer_width("right").id,
       data_side="right"
     )
     
     # Wrap content in scrollable container
     content_wrapper = Div(
-      *self.right_drawer.get_content(),
+      *[
+          (
+              Div(cls="divider") if index > 0 else None,
+              group_ft,
+              *[item for item in self.right_drawer.get_content()[group_name]]
+          )
+          for index, (group_name, group_ft) in enumerate(self.right_drawer.get_groups())
+      ],
       cls="mf-layout-drawer-content"
     )
     
@@ -287,15 +312,29 @@ class Layout(SingleInstance):
     )
   
   def _mk_left_drawer_icon(self):
-    return mk.icon(right_drawer_icon if self._state.left_drawer_open else left_drawer_icon,
+    return mk.icon(left_drawer_contract if self._state.left_drawer_open else left_drawer_expand,
                    id=f"{self._id}_ldi",
                    command=self.commands.toggle_drawer("left"))
   
   def _mk_right_drawer_icon(self):
-    return mk.icon(right_drawer_icon if self._state.left_drawer_open else left_drawer_icon,
+    return mk.icon(right_drawer_contract if self._state.right_drawer_open else right_drawer_expand,
                    id=f"{self._id}_rdi",
                    command=self.commands.toggle_drawer("right"))
   
+  @staticmethod
+  def _mk_content_wrapper(content: Content, show_group_name: bool = True, horizontal: bool = False):
+    return Div(
+      *[
+          (
+              Div(cls=f"divider {'divider-horizontal' if horizontal else ''}") if index > 0 else None,
+              group_ft if show_group_name else None,
+              *[item for item in content.get_content()[group_name]]
+          )
+          for index, (group_name, group_ft) in enumerate(content.get_groups())
+      ],
+      cls="mf-layout-drawer-content"
+    )
+  
   def render(self):
     """
     Render the complete layout.
@@ -306,12 +345,13 @@ class Layout(SingleInstance):
     
     # Wrap everything in a container div
     return Div(
+      Div(id=f"tt_{self._id}", cls="mf-tooltip-container"),  # container for the tooltips
       self._mk_header(),
       self._mk_left_drawer(),
       self._mk_main(),
       self._mk_right_drawer(),
       self._mk_footer(),
-      Script(f"initLayoutResizer('{self._id}');"),
+      Script(f"initLayout('{self._id}');"),
       id=self._id,
       cls="mf-layout",
     )

src/myfasthtml/controls/Mouse.py

@@ -7,6 +7,12 @@ from myfasthtml.core.instances import MultipleInstance
 
 
 class Mouse(MultipleInstance):
+  """
+  Represents a mechanism to manage mouse event combinations and their associated commands.
+
+  This class is used to add, manage, and render mouse event sequences with corresponding
+  commands, providing a flexible way to handle mouse interactions programmatically.
+  """
   def __init__(self, parent, _id=None, combinations=None):
     super().__init__(parent, _id=_id)
     self.combinations = combinations or {}

src/myfasthtml/controls/Panel.py

@@ -0,0 +1,111 @@
+from dataclasses import dataclass
+from typing import Literal
+
+from fasthtml.components import Div
+from fasthtml.xtend import Script
+
+from myfasthtml.controls.BaseCommands import BaseCommands
+from myfasthtml.core.commands import Command
+from myfasthtml.core.instances import MultipleInstance
+
+
+@dataclass
+class PanelConf:
+  left: bool = False
+  right: bool = True
+
+
+class Commands(BaseCommands):
+  def toggle_side(self, side: Literal["left", "right"]):
+    return Command("TogglePanelSide", f"Toggle {side} side panel", self._owner.toggle_side, side)
+  
+  def update_side_width(self, side: Literal["left", "right"]):
+    """
+    Create a command to update panel's side width.
+
+    Args:
+        side: Which panel's side to update ("left" or "right")
+
+    Returns:
+        Command: Command object for updating panel's side width
+    """
+    return Command(
+      f"UpdatePanelSideWidth_{side}",
+      f"Update {side} side panel width",
+      self._owner.update_side_width,
+      side
+    )
+
+
+class Panel(MultipleInstance):
+  """
+  Represents a user interface panel that supports customizable left, main, and right components.
+
+  The `Panel` class is used to create and manage a panel layout with optional left, main,
+  and right sections. It provides functionality to set the components of the panel, toggle
+  sides, and adjust the width of the sides dynamically. The class also handles rendering
+  the panel with appropriate HTML elements and JavaScript for interactivity.
+  """
+  
+  def __init__(self, parent, conf=None, _id=None):
+    super().__init__(parent, _id=_id)
+    self.conf = conf or PanelConf()
+    self.commands = Commands(self)
+    self._main = None
+    self._right = None
+    self._left = None
+  
+  def update_side_width(self, side, width):
+    pass
+  
+  def toggle_side(self, side):
+    pass
+  
+  def set_main(self, main):
+    self._main = main
+    return self
+  
+  def set_right(self, right):
+    self._right = right
+    return Div(self._right, id=f"{self._id}_r")
+  
+  def set_left(self, left):
+    self._left = left
+    return Div(self._left, id=f"{self._id}_l")
+  
+  def _mk_right(self):
+    if not self.conf.right:
+      return None
+    
+    resizer = Div(
+      cls="mf-resizer mf-resizer-right",
+      data_command_id=self.commands.update_side_width("right").id,
+      data_side="right"
+    )
+    
+    return Div(resizer, Div(self._right, id=f"{self._id}_r"), cls="mf-panel-right")
+  
+  def _mk_left(self):
+    if not self.conf.left:
+      return None
+    
+    resizer = Div(
+      cls="mf-resizer mf-resizer-left",
+      data_command_id=self.commands.update_side_width("left").id,
+      data_side="left"
+    )
+    
+    return Div(Div(self._left, id=f"{self._id}_l"), resizer, cls="mf-panel-left")
+  
+  def render(self):
+    return Div(
+      self._mk_left(),
+      Div(self._main, cls="mf-panel-main"),
+      self._mk_right(),
+      Script(f"initResizer('{self._id}');"),
+      cls="mf-panel",
+      id=self._id,
+    )
+  
+  def __ft__(self):
+    return self.render()

src/myfasthtml/controls/Properties.py

@@ -0,0 +1,50 @@
+from fasthtml.components import Div
+from myutils.ProxyObject import ProxyObject
+
+from myfasthtml.core.instances import MultipleInstance
+
+
+class Properties(MultipleInstance):
+  def __init__(self, parent, obj=None, groups: dict = None, _id=None):
+    super().__init__(parent, _id=_id)
+    self.obj = obj
+    self.groups = groups
+    self.properties_by_group = self._create_properties_by_group()
+  
+  def set_obj(self, obj, groups: dict = None):
+    self.obj = obj
+    self.groups = groups
+    self.properties_by_group = self._create_properties_by_group()
+  
+  def render(self):
+    return Div(
+      *[
+          Div(
+            Div(group_name if group_name is not None else "", cls="mf-properties-group-header"),
+            Div(
+              *[
+                  Div(
+                    Div(k, cls="mf-properties-key"),
+                    Div(str(v), cls="mf-properties-value", title=str(v)),
+                    cls="mf-properties-row"
+                  )
+                  for k, v in proxy.as_dict().items()
+              ],
+              cls="mf-properties-group-content"
+            ),
+            cls="mf-properties-group-card"
+          )
+          for group_name, proxy in self.properties_by_group.items()
+      ],
+      id=self._id,
+      cls="mf-properties"
+    )
+  
+  def _create_properties_by_group(self):
+    if self.groups is None:
+      return {None: ProxyObject(self.obj, {"*": ""})}
+    
+    return {k: ProxyObject(self.obj, v) for k, v in self.groups.items()}
+  
+  def __ft__(self):
+    return self.render()

src/myfasthtml/controls/Search.py

@@ -21,6 +21,21 @@ class Commands(BaseCommands):
 
 
 class Search(MultipleInstance):
+  """
+  Represents a component for managing and filtering a list of items.
+  It uses fuzzy matching and subsequence matching to filter items.
+
+  :ivar items_names: The name of the items used to filter.
+  :type items_names: str
+  :ivar items: The first set of items to filter.
+  :type items: list
+  :ivar filtered: A copy of the `items` list, representing the filtered items after a search operation.
+  :type filtered: list
+  :ivar get_attr: Callable function to extract string values from items for filtering.
+  :type get_attr: Callable[[Any], str]
+  :ivar template: Callable function to define how filtered items are rendered.
+  :type template: Callable[[Any], Any]
+  """
   def __init__(self,
                parent: BaseInstance,
                _id=None,

src/myfasthtml/controls/TabsManager.py

@@ -102,7 +102,11 @@ class TabsManager(MultipleInstance):
     tab_config = self._state.tabs[tab_id]
     if tab_config["component_type"] is None:
       return None
-    return InstancesManager.get(self._session,  tab_config["component_id"])
+    try:
+      return InstancesManager.get(self._session, tab_config["component_id"])
+    except Exception as e:
+      logger.error(f"Error while retrieving tab content: {e}")
+      return Div("Tab not found.")
   
   @staticmethod
   def _get_tab_count():
@@ -203,6 +207,11 @@ class TabsManager(MultipleInstance):
       logger.debug(f"  Content already exists. Just switch.")
       return self._mk_tabs_controller()
   
+  def switch_tab(self, tab_id, label, component, activate=True):
+    logger.debug(f"switch_tab {label=}, component={component}, activate={activate}")
+    self._add_or_update_tab(tab_id, label, component, activate)
+    return self.show_tab(tab_id) #
+  
   def close_tab(self, tab_id: str):
     """
     Close a tab and remove it from the tabs manager.
@@ -382,6 +391,34 @@ class TabsManager(MultipleInstance):
   def _get_tab_list(self):
     return [self._state.tabs[tab_id] for tab_id in self._state.tabs_order if tab_id in self._state.tabs]
   
+  def _add_or_update_tab(self, tab_id, label, component, activate):
+    state = self._state.copy()
+    
+    # Extract component ID if the component has a get_id() method
+    component_type, component_id = None, None
+    if isinstance(component, BaseInstance):
+      component_type = component.get_prefix() if isinstance(component, BaseInstance) else type(component).__name__
+      component_id = component.get_id()
+    
+    # Add tab metadata to state
+    state.tabs[tab_id] = {
+        'id': tab_id,
+        'label': label,
+        'component_type': component_type,
+        'component_id': component_id
+    }
+    
+    # Add the content
+    state._tabs_content[tab_id] = component
+    
+    # Activate tab if requested
+    if activate:
+      state.active_tab = tab_id
+    
+    # finally, update the state
+    self._state.update(state)
+    self._search.set_items(self._get_tab_list())
+  
   def update_boundaries(self):
     return Script(f"updateBoundaries('{self._id}');")
   

src/myfasthtml/controls/TreeView.py

@@ -0,0 +1,399 @@
+"""
+TreeView component for hierarchical data visualization with inline editing.
+
+This component provides an interactive tree structure with expand/collapse,
+selection, and inline editing capabilities.
+"""
+import uuid
+from dataclasses import dataclass, field
+from typing import Optional
+
+from fasthtml.components import Div, Input, Span
+
+from myfasthtml.controls.BaseCommands import BaseCommands
+from myfasthtml.controls.Keyboard import Keyboard
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+from myfasthtml.core.dbmanager import DbObject
+from myfasthtml.core.instances import MultipleInstance
+from myfasthtml.icons.fluent_p1 import chevron_right20_regular, edit20_regular
+from myfasthtml.icons.fluent_p2 import chevron_down20_regular, add_circle20_regular, delete20_regular
+
+
+@dataclass
+class TreeNode:
+  """
+  Represents a node in the tree structure.
+
+  Attributes:
+      id: Unique identifier (auto-generated UUID if not provided)
+      label: Display text for the node
+      type: Node type for icon mapping
+      parent: ID of parent node (None for root)
+      children: List of child node IDs
+  """
+  id: str = field(default_factory=lambda: str(uuid.uuid4()))
+  label: str = ""
+  type: str = "default"
+  parent: Optional[str] = None
+  children: list[str] = field(default_factory=list)
+
+
+class TreeViewState(DbObject):
+  """
+  Persistent state for TreeView component.
+
+  Attributes:
+      items: Dictionary mapping node IDs to TreeNode instances
+      opened: List of expanded node IDs
+      selected: Currently selected node ID
+      editing: Node ID currently being edited (None if not editing)
+      icon_config: Mapping of node types to icon identifiers
+  """
+  
+  def __init__(self, owner):
+    super().__init__(owner)
+    with self.initializing():
+      self.items: dict[str, TreeNode] = {}
+      self.opened: list[str] = []
+      self.selected: Optional[str] = None
+      self.editing: Optional[str] = None
+      self.icon_config: dict[str, str] = {}
+
+
+class Commands(BaseCommands):
+  """Command handlers for TreeView actions."""
+  
+  def toggle_node(self, node_id: str):
+    """Create command to expand/collapse a node."""
+    return Command(
+      "ToggleNode",
+      f"Toggle node {node_id}",
+      self._owner._toggle_node,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def add_child(self, parent_id: str):
+    """Create command to add a child node."""
+    return Command(
+      "AddChild",
+      f"Add child to {parent_id}",
+      self._owner._add_child,
+      parent_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def add_sibling(self, node_id: str):
+    """Create command to add a sibling node."""
+    return Command(
+      "AddSibling",
+      f"Add sibling to {node_id}",
+      self._owner._add_sibling,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def start_rename(self, node_id: str):
+    """Create command to start renaming a node."""
+    return Command(
+      "StartRename",
+      f"Start renaming {node_id}",
+      self._owner._start_rename,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def save_rename(self, node_id: str):
+    """Create command to save renamed node."""
+    return Command(
+      "SaveRename",
+      f"Save rename for {node_id}",
+      self._owner._save_rename,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def cancel_rename(self):
+    """Create command to cancel renaming."""
+    return Command(
+      "CancelRename",
+      "Cancel rename",
+      self._owner._cancel_rename
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def delete_node(self, node_id: str):
+    """Create command to delete a node."""
+    return Command(
+      "DeleteNode",
+      f"Delete node {node_id}",
+      self._owner._delete_node,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+  
+  def select_node(self, node_id: str):
+    """Create command to select a node."""
+    return Command(
+      "SelectNode",
+      f"Select node {node_id}",
+      self._owner._select_node,
+      node_id
+    ).htmx(target=f"#{self._owner.get_id()}")
+
+
+class TreeView(MultipleInstance):
+  """
+  Interactive TreeView component with hierarchical data visualization.
+
+  Supports:
+  - Expand/collapse nodes
+  - Add child/sibling nodes
+  - Inline rename
+  - Delete nodes
+  - Node selection
+  """
+  
+  def __init__(self, parent, items: Optional[dict] = None, _id: Optional[str] = None):
+    """
+    Initialize TreeView component.
+
+    Args:
+        parent: Parent instance
+        items: Optional initial items dictionary {node_id: TreeNode}
+        _id: Optional custom ID
+    """
+    super().__init__(parent, _id=_id)
+    self._state = TreeViewState(self)
+    self.commands = Commands(self)
+    
+    if items:
+      self._state.items = items
+  
+  def set_icon_config(self, config: dict[str, str]):
+    """
+    Set icon configuration for node types.
+
+    Args:
+        config: Dictionary mapping node types to icon identifiers
+               Format: {type: "provider.icon_name"}
+    """
+    self._state.icon_config = config
+   
+  def add_node(self, node: TreeNode, parent_id: Optional[str] = None, insert_index: Optional[int] = None):
+    """
+    Add a node to the tree.
+
+    Args:
+        node: TreeNode instance to add
+        parent_id: Optional parent node ID (None for root)
+        insert_index: Optional index to insert at in parent's children list.
+                     If None, appends to end. If provided, inserts at that position.
+    """
+    self._state.items[node.id] = node
+    node.parent = parent_id
+    
+    if parent_id and parent_id in self._state.items:
+      parent = self._state.items[parent_id]
+      if node.id not in parent.children:
+        if insert_index is not None:
+          parent.children.insert(insert_index, node.id)
+        else:
+          parent.children.append(node.id)
+  
+  def expand_all(self):
+    """Expand all nodes that have children."""
+    for node_id, node in self._state.items.items():
+      if node.children and node_id not in self._state.opened:
+        self._state.opened.append(node_id)
+  
+  def _toggle_node(self, node_id: str):
+    """Toggle expand/collapse state of a node."""
+    if node_id in self._state.opened:
+      self._state.opened.remove(node_id)
+    else:
+      self._state.opened.append(node_id)
+    return self
+  
+  def _add_child(self, parent_id: str, new_label: Optional[str] = None):
+    """Add a child node to a parent."""
+    if parent_id not in self._state.items:
+      raise ValueError(f"Parent node {parent_id} does not exist")
+    
+    parent = self._state.items[parent_id]
+    new_node = TreeNode(
+      label=new_label or "New Node",
+      type=parent.type
+    )
+    
+    self.add_node(new_node, parent_id=parent_id)
+    
+    # Auto-expand parent
+    if parent_id not in self._state.opened:
+      self._state.opened.append(parent_id)
+    
+    return self
+  
+  def _add_sibling(self, node_id: str, new_label: Optional[str] = None):
+    """Add a sibling node next to a node."""
+    if node_id not in self._state.items:
+      raise ValueError(f"Node {node_id} does not exist")
+    
+    node = self._state.items[node_id]
+    
+    if node.parent is None:
+      raise ValueError("Cannot add sibling to root node")
+    
+    parent = self._state.items[node.parent]
+    new_node = TreeNode(
+      label=new_label or "New Node",
+      type=node.type
+    )
+    
+    # Insert after current node
+    insert_idx = parent.children.index(node_id) + 1
+    self.add_node(new_node, parent_id=node.parent, insert_index=insert_idx)
+    
+    return self
+  
+  def _start_rename(self, node_id: str):
+    """Start renaming a node (sets editing state)."""
+    if node_id not in self._state.items:
+      raise ValueError(f"Node {node_id} does not exist")
+    
+    self._state.editing = node_id
+    return self
+  
+  def _save_rename(self, node_id: str, node_label: str):
+    """Save renamed node with new label."""
+    if node_id not in self._state.items:
+      raise ValueError(f"Node {node_id} does not exist")
+    
+    self._state.items[node_id].label = node_label
+    self._state.editing = None
+    return self
+  
+  def _cancel_rename(self):
+    """Cancel renaming operation."""
+    self._state.editing = None
+    return self
+  
+  def _delete_node(self, node_id: str):
+    """Delete a node (only if it has no children)."""
+    if node_id not in self._state.items:
+      raise ValueError(f"Node {node_id} does not exist")
+    
+    node = self._state.items[node_id]
+    
+    if node.children:
+      raise ValueError(f"Cannot delete node {node_id} with children")
+    
+    # Remove from parent's children list
+    if node.parent and node.parent in self._state.items:
+      parent = self._state.items[node.parent]
+      parent.children.remove(node_id)
+    
+    # Remove from state
+    del self._state.items[node_id]
+    
+    if node_id in self._state.opened:
+      self._state.opened.remove(node_id)
+    
+    if self._state.selected == node_id:
+      self._state.selected = None
+    
+    return self
+  
+  def _select_node(self, node_id: str):
+    """Select a node."""
+    if node_id not in self._state.items:
+      raise ValueError(f"Node {node_id} does not exist")
+    
+    self._state.selected = node_id
+    return self
+  
+  def _render_action_buttons(self, node_id: str):
+    """Render action buttons for a node (visible on hover)."""
+    return Div(
+      mk.icon(add_circle20_regular, command=self.commands.add_child(node_id)),
+      mk.icon(edit20_regular, command=self.commands.start_rename(node_id)),
+      mk.icon(delete20_regular, command=self.commands.delete_node(node_id)),
+      cls="mf-treenode-actions"
+    )
+  
+  def _render_node(self, node_id: str, level: int = 0):
+    """
+    Render a single node and its children recursively.
+
+    Args:
+        node_id: ID of node to render
+        level: Indentation level
+
+    Returns:
+        Div containing the node and its children
+    """
+    node = self._state.items[node_id]
+    is_expanded = node_id in self._state.opened
+    is_selected = node_id == self._state.selected
+    is_editing = node_id == self._state.editing
+    has_children = len(node.children) > 0
+    
+    # Toggle icon
+    toggle = mk.icon(
+      chevron_down20_regular if is_expanded else chevron_right20_regular if has_children else None,
+      command=self.commands.toggle_node(node_id))
+    
+    # Label or input for editing
+    if is_editing:
+      label_element = mk.mk(Input(
+        name="node_label",
+        value=node.label,
+        cls="mf-treenode-input input input-sm"
+      ), command=self.commands.save_rename(node_id))
+    else:
+      label_element = mk.mk(
+        Span(node.label, cls="mf-treenode-label text-sm"),
+        command=self.commands.select_node(node_id)
+      )
+    
+    # Node element
+    node_element = Div(
+      toggle,
+      label_element,
+      self._render_action_buttons(node_id),
+      cls=f"mf-treenode flex {'selected' if is_selected and not is_editing else ''}",
+      style=f"padding-left: {level * 20}px"
+    )
+    
+    # Children (if expanded)
+    children_elements = []
+    if is_expanded and has_children:
+      for child_id in node.children:
+        children_elements.append(
+          self._render_node(child_id, level + 1)
+        )
+    
+    return Div(
+      node_element,
+      *children_elements,
+      cls="mf-treenode-container",
+      data_node_id=node_id,
+    )
+  
+  def render(self):
+    """
+    Render the complete TreeView.
+
+    Returns:
+        Div: Complete TreeView HTML structure
+    """
+    # Find root nodes (nodes without parent)
+    root_nodes = [
+        node_id for node_id, node in self._state.items.items()
+        if node.parent is None
+    ]
+    
+    return Div(
+      *[self._render_node(node_id) for node_id in root_nodes],
+      Keyboard(self, {"esc": self.commands.cancel_rename()}, _id="-keyboard"),
+      id=self._id,
+      cls="mf-treeview"
+    )
+  
+  def __ft__(self):
+    """FastHTML magic method for rendering."""
+    return self.render()

src/myfasthtml/controls/VisNetwork.py

@@ -25,19 +25,33 @@ class VisNetworkState(DbObject):
           },
           "physics": {"enabled": True}
       }
+      self.events_handlers: dict = {}  # {event_name: command_url}
 
 
 class VisNetwork(MultipleInstance):
-  def __init__(self, parent, _id=None, nodes=None, edges=None, options=None):
+  def __init__(self, parent, _id=None, nodes=None, edges=None, options=None, events_handlers=None):
     super().__init__(parent, _id=_id)
     logger.debug(f"VisNetwork created with id: {self._id}")
     
+    # possible events (expected in snake_case
+    # - select_node → selectNode
+    # - select → select
+    # - click → click
+    # - double_click → doubleClick
+    
     self._state = VisNetworkState(self)
-    self._update_state(nodes, edges, options)
+    
+    # Convert Commands to URLs
+    handlers_htmx_options = {
+        event_name: command.ajax_htmx_options()
+        for event_name, command in events_handlers.items()
+    } if events_handlers else {}
+    
+    self._update_state(nodes, edges, options, handlers_htmx_options)
   
-  def _update_state(self, nodes, edges, options):
-    logger.debug(f"Updating VisNetwork state with {nodes=}, {edges=}, {options=}")
-    if not nodes and not edges and not options:
+  def _update_state(self, nodes, edges, options, events_handlers=None):
+    logger.debug(f"Updating VisNetwork state with {nodes=}, {edges=}, {options=}, {events_handlers=}")
+    if not nodes and not edges and not options and not events_handlers:
       return
     
     state = self._state.copy()
@@ -47,6 +61,8 @@ class VisNetwork(MultipleInstance):
       state.edges = edges
     if options is not None:
       state.options = options
+    if events_handlers is not None:
+      state.events_handlers = events_handlers
     
     self._state.update(state)
   
@@ -70,6 +86,34 @@ class VisNetwork(MultipleInstance):
     # Convert Python options to JS
     js_options = json.dumps(self._state.options, indent=2)
     
+    # Map Python event names to vis-network event names
+    event_name_map = {
+        "select_node": "selectNode",
+        "select": "select",
+        "click": "click",
+        "double_click": "doubleClick"
+    }
+    
+    # Generate event handlers JavaScript
+    event_handlers_js = ""
+    for event_name, command_htmx_options in self._state.events_handlers.items():
+      vis_event_name = event_name_map.get(event_name, event_name)
+      event_handlers_js += f"""
+              network.on('{vis_event_name}', function(params) {{
+                const event_data = {{
+                  event_name: '{event_name}',
+                  nodes: params.nodes,
+                  edges: params.edges,
+                  pointer: params.pointer
+                }};
+                htmx.ajax('POST', '{command_htmx_options['url']}', {{
+                  values: {{event_data: JSON.stringify(event_data)}},
+                  target: '{command_htmx_options['target']}',
+                  swap: '{command_htmx_options['swap']}'
+                }});
+              }});
+"""
+    
     return (
         Div(
           id=self._id,
@@ -92,6 +136,7 @@ class VisNetwork(MultipleInstance):
               }};
               const options = {js_options};
               const network = new vis.Network(container, data, options);
+              {event_handlers_js}
             }})();
         """)
     )

src/myfasthtml/controls/datagrid_objects.py

@@ -0,0 +1,49 @@
+from dataclasses import dataclass, field
+
+from myfasthtml.core.constants import ColumnType, DEFAULT_COLUMN_WIDTH, ViewType
+
+
+@dataclass
+class DataGridRowState:
+  row_id: int
+  visible: bool = True
+  height: int | None = None
+
+@dataclass
+class DataGridColumnState:
+  col_id: str  # name of the column: cannot be changed
+  col_index: int  # index of the column in the dataframe: cannot be changed
+  title: str = None
+  type: ColumnType = ColumnType.Text
+  visible: bool = True
+  usable: bool = True
+  width: int = DEFAULT_COLUMN_WIDTH
+
+
+@dataclass
+class DatagridEditionState:
+  under_edition: tuple[int, int] | None = None
+  previous_under_edition: tuple[int, int] | None = None
+
+
+@dataclass
+class DatagridSelectionState:
+  selected: tuple[int, int] | None = None
+  last_selected: tuple[int, int] | None = None
+  selection_mode: str = None  # valid values are "row", "column" or None for "cell"
+  extra_selected: list[tuple[str, str | int]] = field(default_factory=list)  # list(tuple(selection_mode, element_id))
+  last_extra_selected: tuple[int, int] = None
+
+
+@dataclass
+class DataGridHeaderFooterConf:
+  conf: dict[str, str] = field(default_factory=dict)  # first 'str' is the column id
+
+
+
+
+@dataclass
+class DatagridView:
+  name: str
+  type: ViewType = ViewType.Table
+  columns: list[DataGridColumnState] = None

src/myfasthtml/controls/helpers.py

@@ -15,6 +15,19 @@ class mk:
   
   @staticmethod
   def button(element, command: Command = None, binding: Binding = None, **kwargs):
+    """
+    Defines a static method for creating a Button object with specific configurations.
+
+    This method constructs a Button instance by wrapping an element with
+    additional configurations such as commands and bindings. Any extra keyword
+    arguments are passed when creating the Button.
+
+    :param element: The underlying widget or element to be wrapped in a Button.
+    :param command: An optional command to associate with the Button. Defaults to None.
+    :param binding: An optional event binding to associate with the Button. Defaults to None.
+    :param kwargs: Additional keyword arguments to further configure the Button.
+    :return: A fully constructed Button instance with the specified configurations.
+    """
     return mk.mk(Button(element, **kwargs), command=command, binding=binding)
   
   @staticmethod
@@ -33,19 +46,45 @@ class mk:
     )
   
   @staticmethod
-  def icon(icon, size=20,
+  def icon(icon,
+           size=20,
            can_select=True,
            can_hover=False,
+           tooltip=None,
            cls='',
            command: Command = None,
            binding: Binding = None,
            **kwargs):
+    """
+    Generates an icon element with customizable properties for size, class, and interactivity.
+
+    This method creates an icon element wrapped in a container with optional classes
+    and event bindings. The icon can be styled and its behavior defined using the parameters
+    provided, allowing for dynamic and reusable UI components.
+
+    :param icon: The icon to display inside the container.
+    :param size: The size of the icon, specified in pixels. Defaults to 20.
+    :param can_select: Indicates whether the icon can be selected. Defaults to True.
+    :param can_hover: Indicates whether the icon reacts to hovering. Defaults to False.
+    :param tooltip:
+    :param cls: A string of custom CSS classes to be added to the icon container.
+    :param command: The command object defining the function to be executed on icon interaction.
+    :param binding: The binding object for configuring additional event listeners on the icon.
+    :param kwargs: Additional keyword arguments for configuring attributes and behaviors of the
+                   icon element.
+    :return: A styled and interactive icon element embedded inside a container, configured
+             with the defined classes, size, and behaviors.
+    """
     merged_cls = merge_classes(f"mf-icon-{size}",
                                'icon-btn' if can_select else '',
                                'mmt-btn' if can_hover else '',
                                cls,
                                kwargs)
     
+    if tooltip:
+      merged_cls = merge_classes(merged_cls, "mf-tooltip")
+      kwargs["data-tooltip"] = tooltip
+    
     return mk.mk(Div(icon, cls=merged_cls, **kwargs), command=command, binding=binding)
   
   @staticmethod

src/myfasthtml/core/commands.py

@@ -1,4 +1,5 @@
 import inspect
+import json
 import uuid
 from typing import Optional
 
@@ -97,6 +98,14 @@ class BaseCommand:
   def url(self):
     return f"{ROUTE_ROOT}{Routes.Commands}?c_id={self.id}"
   
+  def ajax_htmx_options(self):
+    return {
+        "url": self.url,
+        "target": self._htmx_extra.get("hx-target", "this"),
+        "swap": self._htmx_extra.get("hx-swap", "outerHTML"),
+        "values": {}
+    }
+  
   def get_ft(self):
     return self._ft
   
@@ -126,7 +135,7 @@ class Command(BaseCommand):
   def __init__(self, name, description, callback, *args, **kwargs):
     super().__init__(name, description)
     self.callback = callback
-    self.callback_parameters = dict(inspect.signature(callback).parameters)
+    self.callback_parameters = dict(inspect.signature(callback).parameters) if callback else {}
     self.args = args
     self.kwargs = kwargs
   
@@ -141,8 +150,17 @@ class Command(BaseCommand):
         return float(value)
       elif param.annotation == list:
         return value.split(",")
+      elif param.annotation == dict:
+        return json.loads(value)
     return value
   
+  def ajax_htmx_options(self):
+    res = super().ajax_htmx_options()
+    if self.kwargs:
+      res["values"] |= self.kwargs
+      res["values"]["c_id"] = f"{self.id}"  # cannot be overridden
+    return res
+  
   def execute(self, client_response: dict = None):
     ret_from_bindings = []
     

src/myfasthtml/core/constants.py

@@ -1,5 +1,39 @@
+from enum import Enum
+
+DEFAULT_COLUMN_WIDTH = 100
+
 ROUTE_ROOT = "/myfasthtml"
 
+
 class Routes:
   Commands = "/commands"
-  Bindings = "/bindings"
+  Bindings = "/bindings"
+
+
+class ColumnType(Enum):
+  RowIndex = "RowIndex"
+  Text = "Text"
+  Number = "Number"
+  Datetime = "DateTime"
+  Bool = "Boolean"
+  Choice = "Choice"
+  List = "List"
+
+
+class ViewType(Enum):
+  Table = "Table"
+  Chart = "Chart"
+  Form = "Form"
+
+
+class FooterAggregation(Enum):
+  Sum = "Sum"
+  Mean = "Mean"
+  Min = "Min"
+  Max = "Max"
+  Count = "Count"
+  FilteredSum = "FilteredSum"
+  FilteredMean = "FilteredMean"
+  FilteredMin = "FilteredMin"
+  FilteredMax = "FilteredMax"
+  FilteredCount = "FilteredCount"

src/myfasthtml/core/dbmanager.py

@@ -10,6 +10,7 @@ from myfasthtml.core.utils import retrieve_user_info
 class DbManager(SingleInstance):
   def __init__(self, parent, root=".myFastHtmlDb", auto_register: bool = True):
     super().__init__(parent, auto_register=auto_register)
+    
     self.db = DbEngine(root=root)
   
   def save(self, entry, obj):
@@ -38,7 +39,7 @@ class DbObject:
   
   def __init__(self, owner: BaseInstance, name=None, db_manager=None):
     self._owner = owner
-    self._name = name or self.__class__.__name__
+    self._name = name or owner.get_full_id()
     self._db_manager = db_manager or DbManager(self._owner)
     
     self._finalize_initialization()
@@ -111,6 +112,7 @@ class DbObject:
         setattr(self, k, v)
     self._save_self()
     self._initializing = old_state
+    return self
   
   def copy(self):
     as_dict = self._get_properties().copy()

src/myfasthtml/core/instances.py

@@ -84,7 +84,7 @@ class BaseInstance:
     return self._prefix
   
   def get_full_id(self) -> str:
-    return f"{InstancesManager.get_session_id(self._session)}-{self._id}"
+    return f"{InstancesManager.get_session_id(self._session)}#{self._id}"
   
   def get_full_parent_id(self) -> Optional[str]:
     parent = self.get_parent()
@@ -176,11 +176,22 @@ class InstancesManager:
     :param instance_id:
     :return:
     """
-    key = (InstancesManager.get_session_id(session), instance_id)
+    session_id = InstancesManager.get_session_id(session)
+    key = (session_id, instance_id)
     return InstancesManager.instances[key]
   
+  @staticmethod
+  def get_by_type(session: dict, cls: type):
+    session_id = InstancesManager.get_session_id(session)
+    res = [i for s, i in InstancesManager.instances.items() if s[0] == session_id and isinstance(i, cls)]
+    assert len(res) <= 1, f"Multiple instances of type {cls.__name__} found"
+    assert len(res) > 0, f"No instance of type {cls.__name__} found"
+    return res[0]
+  
   @staticmethod
   def get_session_id(session):
+    if isinstance(session, str):
+      return session
     if session is None:
       return "** NOT LOGGED IN **"
     if "user_info" not in session:

src/myfasthtml/core/network_utils.py

@@ -3,6 +3,7 @@ from collections.abc import Callable
 ROOT_COLOR = "#ff9999"
 GHOST_COLOR = "#cccccc"
 
+
 def from_nested_dict(trees: list[dict]) -> tuple[list, list]:
   """
   Convert a list of nested dictionaries to vis.js nodes and edges format.

src/myfasthtml/test/matcher.py

@@ -1,11 +1,16 @@
 import re
 from dataclasses import dataclass
+from typing import Optional, Any
 
 from fastcore.basics import NotStr
+from fastcore.xml import FT
 
-from myfasthtml.core.utils import quoted_str
+from myfasthtml.core.commands import BaseCommand
+from myfasthtml.core.utils import quoted_str, snake_to_pascal
 from myfasthtml.test.testclient import MyFT
 
+MISSING_ATTR = "** MISSING **"
+
 
 class Predicate:
   def __init__(self, value):
@@ -15,7 +20,18 @@ class Predicate:
     raise NotImplementedError
   
   def __str__(self):
-    return f"{self.__class__.__name__}({self.value if self.value is not None else ''})"
+    if self.value is None:
+      str_value = ''
+    elif isinstance(self.value, str):
+      str_value = self.value
+    elif isinstance(self.value, (list, tuple)):
+      if len(self.value) == 1:
+        str_value = self.value[0]
+      else:
+        str_value = str(self.value)
+    else:
+      str_value = str(self.value)
+    return f"{self.__class__.__name__}({str_value})"
   
   def __repr__(self):
     return f"{self.__class__.__name__}({self.value if self.value is not None else ''})"
@@ -45,20 +61,33 @@ class StartsWith(AttrPredicate):
     return actual.startswith(self.value)
 
 
-class Contains(AttrPredicate):
+class EndsWith(AttrPredicate):
   def __init__(self, value):
     super().__init__(value)
   
   def validate(self, actual):
-    return self.value in actual
+    return actual.endswith(self.value)
+
+
+class Contains(AttrPredicate):
+  def __init__(self, *value, _word=False):
+    super().__init__(value)
+    self._word = _word
+  
+  def validate(self, actual):
+    if self._word:
+      words = actual.split()
+      return all(val in words for val in self.value)
+    else:
+      return all(val in actual for val in self.value)
 
 
 class DoesNotContain(AttrPredicate):
-  def __init__(self, value):
+  def __init__(self, *value):
     super().__init__(value)
   
   def validate(self, actual):
-    return self.value not in actual
+    return all(val not in actual for val in self.value)
 
 
 class AnyValue(AttrPredicate):
@@ -73,6 +102,14 @@ class AnyValue(AttrPredicate):
     return actual is not None
 
 
+class Regex(AttrPredicate):
+  def __init__(self, pattern):
+    super().__init__(pattern)
+  
+  def validate(self, actual):
+    return re.match(self.value, actual) is not None
+
+
 class ChildrenPredicate(Predicate):
   """
   Predicate given as a child of an element.
@@ -114,11 +151,142 @@ class AttributeForbidden(ChildrenPredicate):
     return element
 
 
+class HasHtmx(ChildrenPredicate):
+  def __init__(self, command: BaseCommand = None, **htmx_params):
+    super().__init__(None)
+    self.command = command
+    if command:
+      self.htmx_params = command.get_htmx_params() | htmx_params
+    else:
+      self.htmx_params = htmx_params
+    
+    self.htmx_params = {k.replace("hx_", "hx-"): v for k, v in self.htmx_params.items()}
+  
+  def validate(self, actual):
+    return all(actual.attrs.get(k) == v for k, v in self.htmx_params.items())
+  
+  def to_debug(self, element):
+    for k, v in self.htmx_params.items():
+      element.attrs[k] = v
+    return element
+
+
+class TestObject:
+  def __init__(self, cls, **kwargs):
+    self.cls = cls
+    self.attrs = kwargs
+
+
+class TestIcon(TestObject):
+  def __init__(self, name: Optional[str] = '', command=None):
+    super().__init__("div")
+    self.name = snake_to_pascal(name) if (name and name[0].islower()) else name
+    self.children = [
+        TestObject(NotStr, s=Regex(f'<svg name="\\w+-{self.name}'))
+    ]
+    if command:
+      self.attrs |= command.get_htmx_params()
+  
+  def __str__(self):
+    return f'<div><svg name="{self.name}" .../></div>'
+
+
+class TestIconNotStr(TestObject):
+  def __init__(self, name: Optional[str] = ''):
+    super().__init__(NotStr)
+    self.name = snake_to_pascal(name) if (name and name[0].islower()) else name
+    self.attrs["s"] = Regex(f'<svg name="\\w+-{self.name}')
+  
+  def __str__(self):
+    return f'<svg name="{self.name}" .../>'
+
+
+class TestCommand(TestObject):
+  def __init__(self, name, **kwargs):
+    super().__init__("Command", **kwargs)
+    self.attrs = {"name": name} | kwargs  # name should be first
+
+
+class TestScript(TestObject):
+  def __init__(self, script):
+    super().__init__("script")
+    self.script = script
+    self.children = [
+        NotStr(self.script),
+    ]
+
+
 @dataclass
 class DoNotCheck:
   desc: str = None
 
 
+@dataclass
+class Skip:
+  element: Any
+  desc: str = None
+
+
+def _get_type(x):
+  if hasattr(x, "tag"):
+    return x.tag
+  if isinstance(x, (TestObject, TestIcon)):
+    return x.cls.__name__ if isinstance(x.cls, type) else str(x.cls)
+  return type(x).__name__
+
+
+def _get_attr(x, attr):
+  if hasattr(x, "attrs"):
+    return x.attrs.get(attr, MISSING_ATTR)
+  
+  if not hasattr(x, attr):
+    return MISSING_ATTR
+  
+  return getattr(x, attr, MISSING_ATTR)
+
+
+def _get_attributes(x):
+  """Get the attributes dict from an element."""
+  if hasattr(x, "attrs"):
+    return x.attrs
+  return {}
+
+
+def _get_children(x):
+  """Get the children list from an element."""
+  if hasattr(x, "children"):
+    return x.children
+  return []
+
+
+def _str_element(element, expected=None, keep_open=None):
+  # compare to itself if no expected element is provided
+  if expected is None:
+    expected = element
+  
+  if hasattr(element, "tag"):
+    # the attributes are compared to the expected element
+    elt_attrs = {attr_name: _get_attr(element, attr_name) for attr_name in
+                 [attr_name for attr_name in _get_attributes(expected) if attr_name is not None]}
+    
+    elt_attrs_str = " ".join(f'"{attr_name}"="{attr_value}"' for attr_name, attr_value in elt_attrs.items())
+    tag_str = f"({element.tag} {elt_attrs_str}"
+    
+    # manage the closing tag
+    if keep_open is False:
+      tag_str += " ...)" if len(element.children) > 0 else ")"
+    elif keep_open is True:
+      tag_str += "..." if elt_attrs_str == "" else " ..."
+    else:
+      # close the tag if there are no children
+      not_special_children = [c for c in element.children if not isinstance(c, Predicate)]
+      if len(not_special_children) == 0:  tag_str += ")"
+    return tag_str
+  
+  else:
+    return quoted_str(element)
+
+
 class ErrorOutput:
   def __init__(self, path, element, expected):
     self.path = path
@@ -143,14 +311,14 @@ class ErrorOutput:
     # first render the path hierarchy
     for p in self.path.split(".")[:-1]:
       elt_name, attr_name, attr_value = self._unconstruct_path_item(p)
-      path_str = self._str_element(MyFT(elt_name, {attr_name: attr_value}), keep_open=True)
+      path_str = _str_element(MyFT(elt_name, {attr_name: attr_value}), keep_open=True)
       self._add_to_output(f"{path_str}")
       self.indent += "  "
     
     # then render the element
     if hasattr(self.expected, "tag") and hasattr(self.element, "tag"):
       # display the tag and its attributes
-      tag_str = self._str_element(self.element, self.expected)
+      tag_str = _str_element(self.element, self.expected)
       self._add_to_output(tag_str)
       
       # Try to show where the differences are
@@ -173,7 +341,7 @@ class ErrorOutput:
           
           # display the child
           element_child = self.element.children[element_index]
-          child_str = self._str_element(element_child, expected_child, keep_open=False)
+          child_str = _str_element(element_child, expected_child, keep_open=False)
           self._add_to_output(child_str)
           
           # manage errors (only when the expected is a FT element
@@ -187,6 +355,16 @@ class ErrorOutput:
         
         self.indent = self.indent[:-2]
         self._add_to_output(")")
+    
+    elif isinstance(self.expected, TestObject):
+      cls = _get_type(self.element)
+      attrs = {attr_name: _get_attr(self.element, attr_name) for attr_name in self.expected.attrs}
+      self._add_to_output(f"({cls} {_str_attrs(attrs)})")
+      # Try to show where the differences are
+      error_str = self._detect_error(self.element, self.expected)
+      if error_str:
+        self._add_to_output(error_str)
+    
     else:
       self._add_to_output(str(self.element))
       # Try to show where the differences are
@@ -197,50 +375,36 @@ class ErrorOutput:
   def _add_to_output(self, msg):
     self.output.append(f"{self.indent}{msg}")
   
-  @staticmethod
-  def _str_element(element, expected=None, keep_open=None):
-    # compare to itself if no expected element is provided
-    if expected is None:
-      expected = element
-    
-    if hasattr(element, "tag"):
-      # the attributes are compared to the expected element
-      elt_attrs = {attr_name: element.attrs.get(attr_name, "** MISSING **") for attr_name in
-                   [attr_name for attr_name in expected.attrs if attr_name is not None]}
-      
-      elt_attrs_str = " ".join(f'"{attr_name}"="{attr_value}"' for attr_name, attr_value in elt_attrs.items())
-      tag_str = f"({element.tag} {elt_attrs_str}"
-      
-      # manage the closing tag
-      if keep_open is False:
-        tag_str += " ...)" if len(element.children) > 0 else ")"
-      elif keep_open is True:
-        tag_str += "..." if elt_attrs_str == "" else " ..."
-      else:
-        # close the tag if there are no children
-        not_special_children = [c for c in element.children if not isinstance(c, Predicate)]
-        if len(not_special_children) == 0:  tag_str += ")"
-      return tag_str
-    
-    else:
-      return quoted_str(element)
-  
   def _detect_error(self, element, expected):
-    if hasattr(expected, "tag") and hasattr(element, "tag"):
-      tag_str = len(element.tag) * (" " if element.tag == expected.tag else "^")
-      elt_attrs = {attr_name: element.attrs.get(attr_name, "** MISSING **") for attr_name in expected.attrs}
-      attrs_in_error = [attr_name for attr_name, attr_value in elt_attrs.items() if
-                        not self._matches(attr_value, expected.attrs[attr_name])]
-      if attrs_in_error:
-        elt_attrs_error = " ".join(len(f'"{name}"="{value}"') * ("^" if name in attrs_in_error else " ")
-                                   for name, value in elt_attrs.items())
-        error_str = f" {tag_str} {elt_attrs_error}"
-        return error_str
+    """
+    Detect errors between element and expected, returning a visual marker string.
+    Unified version that handles both FT elements and TestObjects.
+    """
+    # For elements with structure (FT or TestObject)
+    if hasattr(expected, "tag") or isinstance(expected, TestObject):
+      element_type = _get_type(element)
+      expected_type = _get_type(expected)
+      type_error = (" " if element_type == expected_type else "^") * len(element_type)
+      
+      element_attrs = {attr_name: _get_attr(element, attr_name) for attr_name in _get_attributes(expected)}
+      expected_attrs = {attr_name: _get_attr(expected, attr_name) for attr_name in _get_attributes(expected)}
+      attrs_in_error = {attr_name for attr_name, attr_value in element_attrs.items() if
+                        not self._matches(attr_value, expected_attrs[attr_name])}
+      
+      attrs_error = " ".join(
+        len(f'"{name}"="{value}"') * ("^" if name in attrs_in_error else " ")
+        for name, value in element_attrs.items()
+      )
+      
+      if type_error.strip() or attrs_error.strip():
+        return f" {type_error} {attrs_error}"
+      return None
+    
+    # For simple values
     else:
       if not self._matches(element, expected):
         return len(str(element)) * "^"
-    
-    return None
+      return None
   
   @staticmethod
   def _matches(element, expected):
@@ -290,39 +454,221 @@ class ErrorComparisonOutput:
     return "\n".join(output)
 
 
-def matches(actual, expected, path=""):
-  def print_path(p):
-    return f"Path  : '{p}'\n" if p else ""
+class Matcher:
+  """
+  Matcher class for comparing actual and expected elements.
+  Provides flexible comparison with support for predicates, nested structures,
+  and detailed error reporting.
+  """
   
-  def _type(x):
-    return type(x)
+  def __init__(self):
+    self.path = ""
   
-  def _debug(elt):
-    return str(elt) if elt else "None"
+  def matches(self, actual, expected):
+    """
+    Compare actual and expected elements.
+
+    Args:
+      actual: The actual element to compare
+      expected: The expected element or pattern
+
+    Returns:
+      True if elements match, raises AssertionError otherwise
+    """
+    if actual is not None and expected is None:
+      self._assert_error("Actual is not None while expected is None", _actual=actual)
+    
+    if isinstance(expected, DoNotCheck):
+      return True
+    
+    if actual is None and expected is not None:
+      self._assert_error("Actual is None while expected is ", _expected=expected)
+    
+    # set the path
+    current_path = self._get_current_path(actual)
+    original_path = self.path
+    self.path = self.path + "." + current_path if self.path else current_path
+    
+    try:
+      self._match_elements(actual, expected)
+    finally:
+      # restore the original path for sibling comparisons
+      self.path = original_path
+    
+    return True
   
-  def _debug_compare(a, b):
-    actual_out = ErrorOutput(path, a, b)
-    expected_out = ErrorOutput(path, b, b)
+  def _match_elements(self, actual, expected):
+    """Internal method that performs the actual comparison logic."""
+    if isinstance(expected, TestObject) or hasattr(expected, "tag"):
+      self._match_element(actual, expected)
+      return
+    
+    if isinstance(expected, Predicate):
+      assert expected.validate(actual), \
+        self._error_msg(f"The condition '{expected}' is not satisfied.",
+                        _actual=actual,
+                        _expected=expected)
+      return
+    
+    assert _get_type(actual) == _get_type(expected), \
+      self._error_msg("The types are different.", _actual=actual, _expected=expected)
+    
+    if isinstance(expected, (list, tuple)):
+      self._match_list(actual, expected)
+    elif isinstance(expected, dict):
+      self._match_dict(actual, expected)
+    elif isinstance(expected, NotStr):
+      self._match_notstr(actual, expected)
+    else:
+      assert actual == expected, self._error_msg("The values are different",
+                                                 _actual=actual,
+                                                 _expected=expected)
+  
+  def _match_element(self, actual, expected):
+    """Match a TestObject or FT element."""
+    # Validate the type/tag
+    assert _get_type(actual) == _get_type(expected), \
+      self._error_msg("The types are different.", _actual=_get_type(actual), _expected=_get_type(expected))
+    
+    # Special conditions (ChildrenPredicate)
+    expected_children = _get_children(expected)
+    for predicate in [c for c in expected_children if isinstance(c, ChildrenPredicate)]:
+      assert predicate.validate(actual), \
+        self._error_msg(f"The condition '{predicate}' is not satisfied.",
+                        _actual=actual,
+                        _expected=predicate.to_debug(expected))
+    
+    # Compare the attributes
+    expected_attrs = _get_attributes(expected)
+    for expected_attr, expected_value in expected_attrs.items():
+      actual_value = _get_attr(actual, expected_attr)
+      
+      # Check if attribute exists
+      if actual_value == MISSING_ATTR:
+        self._assert_error(f"'{expected_attr}' is not found in Actual. (attributes: {self._str_attrs(actual)})",
+                           _actual=actual,
+                           _expected=expected)
+      
+      # Handle Predicate values
+      if isinstance(expected_value, Predicate):
+        assert expected_value.validate(actual_value), \
+          self._error_msg(f"The condition '{expected_value}' is not satisfied.",
+                          _actual=actual,
+                          _expected=expected)
+      
+      # Handle TestObject recursive matching
+      elif isinstance(expected, TestObject):
+        try:
+          self.matches(actual_value, expected_value)
+        except AssertionError as e:
+          match = re.search(r"Error : (.+?)\n", str(e))
+          if match:
+            self._assert_error(f"{match.group(1)} for '{expected_attr}'.",
+                               _actual=actual_value,
+                               _expected=expected_value)
+          else:
+            self._assert_error(f"The values are different for '{expected_attr}'.",
+                               _actual=actual_value,
+                               _expected=expected_value)
+      
+      # Handle regular value comparison
+      else:
+        assert actual_value == expected_value, \
+          self._error_msg(f"The values are different for '{expected_attr}'.",
+                          _actual=actual,
+                          _expected=expected)
+    
+    # Compare the children (only if present)
+    if expected_children:
+      # Filter out Predicate children
+      expected_children = [c for c in expected_children if not isinstance(c, Predicate)]
+      actual_children = _get_children(actual)
+      
+      if len(actual_children) < len(expected_children):
+        self._assert_error("Actual is lesser than expected.", _actual=actual, _expected=expected)
+      
+      actual_child_index, expected_child_index = 0, 0
+      while expected_child_index < len(expected_children):
+        if actual_child_index >= len(actual_children):
+          self._assert_error("Nothing more to skip.", _actual=actual, _expected=expected)
+        
+        actual_child = actual_children[actual_child_index]
+        expected_child = expected_children[expected_child_index]
+        
+        if isinstance(expected_child, Skip):
+          try:
+            # if this is the element to skip, skip it and continue
+            self._match_element(actual_child, expected_child.element)
+            actual_child_index += 1
+            continue
+          except AssertionError:
+            # otherwise try to match with the following element
+            expected_child_index += 1
+            continue
+        
+        assert self.matches(actual_child, expected_child)
+        
+        actual_child_index += 1
+        expected_child_index += 1
+  
+  def _match_list(self, actual, expected):
+    """Match list or tuple."""
+    if len(actual) < len(expected):
+      self._assert_error("Actual is smaller than expected: ", _actual=actual, _expected=expected)
+    if len(actual) > len(expected):
+      self._assert_error("Actual is bigger than expected: ", _actual=actual, _expected=expected)
+    
+    for actual_child, expected_child in zip(actual, expected):
+      assert self.matches(actual_child, expected_child)
+  
+  def _match_dict(self, actual, expected):
+    """Match dictionary."""
+    if len(actual) < len(expected):
+      self._assert_error("Actual is smaller than expected: ", _actual=actual, _expected=expected)
+    if len(actual) > len(expected):
+      self._assert_error("Actual is bigger than expected: ", _actual=actual, _expected=expected)
+    for k, v in expected.items():
+      assert self.matches(actual[k], v)
+  
+  def _match_notstr(self, actual, expected):
+    """Match NotStr type."""
+    to_compare = _get_attr(actual, "s").lstrip('\n').lstrip()
+    assert to_compare.startswith(expected.s), self._error_msg("Notstr values are different: ",
+                                                              _actual=to_compare,
+                                                              _expected=expected.s)
+  
+  def _print_path(self):
+    """Format the current path for error messages."""
+    return f"Path  : '{self.path}'\n" if self.path else ""
+  
+  def _debug_compare(self, a, b):
+    """Generate a comparison debug output."""
+    actual_out = ErrorOutput(self.path, a, b)
+    expected_out = ErrorOutput(self.path, b, b)
     
     comparison_out = ErrorComparisonOutput(actual_out, expected_out)
     return comparison_out.render()
   
-  def _error_msg(msg, _actual=None, _expected=None):
+  def _error_msg(self, msg, _actual=None, _expected=None):
+    """Generate an error message with debug information."""
     if _actual is None and _expected is None:
       debug_info = ""
     elif _actual is None:
-      debug_info = _debug(_expected)
+      debug_info = self._debug(_expected)
     elif _expected is None:
-      debug_info = _debug(_actual)
+      debug_info = self._debug(_actual)
     else:
-      debug_info = _debug_compare(_actual, _expected)
+      debug_info = self._debug_compare(_actual, _expected)
     
-    return f"{print_path(path)}Error : {msg}\n{debug_info}"
+    return f"{self._print_path()}Error : {msg}\n{debug_info}"
   
-  def _assert_error(msg, _actual=None, _expected=None):
-    assert False, _error_msg(msg, _actual=_actual, _expected=_expected)
+  def _assert_error(self, msg, _actual=None, _expected=None):
+    """Raise an assertion error with formatted message."""
+    assert False, self._error_msg(msg, _actual=_actual, _expected=_expected)
   
+  @staticmethod
   def _get_current_path(elt):
+    """Get the path representation of an element."""
     if hasattr(elt, "tag"):
       res = f"{elt.tag}"
       if "id" in elt.attrs:
@@ -335,134 +681,128 @@ def matches(actual, expected, path=""):
     else:
       return elt.__class__.__name__
   
-  if actual is not None and expected is None:
-    _assert_error("Actual is not None while expected is None", _actual=actual)
+  @staticmethod
+  def _str_attrs(element):
+    """Format attributes as a string."""
+    attrs = _get_attributes(element)
+    return " ".join(f'"{attr_name}"="{attr_value}"' for attr_name, attr_value in attrs.items())
   
-  if isinstance(expected, DoNotCheck):
-    return True
-  
-  if actual is None and expected is not None:
-    _assert_error("Actual is None while expected is ", _expected=expected)
-  
-  # set the path
-  path += "." + _get_current_path(actual) if path else _get_current_path(actual)
-  
-  assert _type(actual) == _type(expected) or (hasattr(actual, "tag") and hasattr(expected, "tag")), \
-    _error_msg("The types are different: ", _actual=actual, _expected=expected)
-  
-  if isinstance(expected, (list, tuple)):
-    if len(actual) < len(expected):
-      _assert_error("Actual is smaller than expected: ", _actual=actual, _expected=expected)
-    if len(actual) > len(expected):
-      _assert_error("Actual is bigger than expected: ", _actual=actual, _expected=expected)
-    
-    for actual_child, expected_child in zip(actual, expected):
-      assert matches(actual_child, expected_child, path=path)
-  
-  elif isinstance(expected, NotStr):
-    to_compare = actual.s.lstrip('\n').lstrip()
-    assert to_compare.startswith(expected.s), _error_msg("Notstr values are different: ",
-                                                         _actual=to_compare,
-                                                         _expected=expected.s)
-  
-  elif hasattr(expected, "tag"):
-    # validate the tags names
-    assert actual.tag == expected.tag, _error_msg("The elements are different.",
-                                                  _actual=actual.tag,
-                                                  _expected=expected.tag)
-    
-    # special conditions
-    for predicate in [c for c in expected.children if isinstance(c, ChildrenPredicate)]:
-      assert predicate.validate(actual), \
-        _error_msg(f"The condition '{predicate}' is not satisfied.",
-                   _actual=actual,
-                   _expected=predicate.to_debug(expected))
-    
-    # compare the attributes
-    for expected_attr, expected_value in expected.attrs.items():
-      assert expected_attr in actual.attrs, _error_msg(f"'{expected_attr}' is not found in Actual.",
-                                                       _actual=actual,
-                                                       _expected=expected)
-      
-      if isinstance(expected_value, Predicate):
-        assert expected_value.validate(actual.attrs[expected_attr]), \
-          _error_msg(f"The condition '{expected_value}' is not satisfied.",
-                     _actual=actual,
-                     _expected=expected)
-      
-      else:
-        assert actual.attrs[expected_attr] == expected.attrs[expected_attr], \
-          _error_msg(f"The values are different for '{expected_attr}': ",
-                     _actual=actual,
-                     _expected=expected)
-    
-    # compare the children
-    expected_children = [c for c in expected.children if not isinstance(c, Predicate)]
-    if len(actual.children) < len(expected_children):
-      _assert_error("Actual is lesser than expected: ", _actual=actual, _expected=expected)
-    
-    for actual_child, expected_child in zip(actual.children, expected_children):
-      assert matches(actual_child, expected_child, path=path)
-  
-  else:
-    assert actual == expected, _error_msg("The values are different: ",
-                                          _actual=actual,
-                                          _expected=expected)
-  
-  return True
+  @staticmethod
+  def _debug(elt):
+    """Format an element for debug output."""
+    return _str_element(elt, keep_open=False) if elt else "None"
+
+
+def matches(actual, expected, path=""):
+  """
+  Compare actual and expected elements.
+
+  This is a convenience wrapper around the Matcher class.
+
+  Args:
+    actual: The actual element to compare
+    expected: The expected element or pattern
+    path: Optional initial path for error reporting
+
+  Returns:
+    True if elements match, raises AssertionError otherwise
+  """
+  matcher = Matcher()
+  matcher.path = path
+  return matcher.matches(actual, expected)
 
 
 def find(ft, expected):
-  res = []
+  """
+  Find all occurrences of an expected element within a FastHTML tree.
+
+  Args:
+    ft: A FastHTML element or list of elements to search in
+    expected: The element pattern to find
+
+  Returns:
+    List of matching elements
+
+  Raises:
+    AssertionError: If no matching elements are found
+  """
   
-  def _type(x):
-    return type(x)
-  
-  def _same(_ft, _expected):
-    if _ft == _expected:
+  def _elements_match(actual, expected):
+    """Check if two elements are the same based on tag, attributes, and children."""
+    if isinstance(expected, DoNotCheck):
       return True
     
-    if _ft.tag != _expected.tag:
+    if isinstance(expected, NotStr):
+      to_compare = _get_attr(actual, "s").lstrip('\n').lstrip()
+      return to_compare.startswith(expected.s)
+    
+    if isinstance(actual, NotStr) and _get_type(actual) != _get_type(expected):
+      return False  # to manage the unexpected __eq__ behavior of NotStr
+    
+    if not isinstance(expected, (TestObject, FT)):
+      return actual == expected
+    
+    # Compare tags
+    if _get_type(actual) != _get_type(expected):
       return False
     
-    for attr in _expected.attrs:
-      if attr not in _ft.attrs or _ft.attrs[attr] != _expected.attrs[attr]:
+    # Compare attributes
+    expected_attrs = _get_attributes(expected)
+    for attr_name, expected_attr_value in expected_attrs.items():
+      actual_attr_value = _get_attr(actual, attr_name)
+      # attribute is missing
+      if actual_attr_value == MISSING_ATTR:
         return False
+      # manage predicate values
+      if isinstance(expected_attr_value, Predicate):
+        return expected_attr_value.validate(actual_attr_value)
+      # finally compare values
+      return actual_attr_value == expected_attr_value
     
-    for expected_child in _expected.children:
-      for ft_child in _ft.children:
-        if _same(ft_child, expected_child):
-          break
-      else:
+    # Compare children recursively
+    expected_children = _get_children(expected)
+    actual_children = _get_children(actual)
+    
+    for expected_child in expected_children:
+      # Check if this expected child exists somewhere in actual children
+      if not any(_elements_match(actual_child, expected_child) for actual_child in actual_children):
         return False
     
     return True
   
-  def _find(current, current_expected):
+  def _search_tree(current, pattern):
+    """Recursively search for pattern in the tree rooted at current."""
+    # Check if current element matches
+    matches = []
+    if _elements_match(current, pattern):
+      matches.append(current)
     
-    if _type(current) != _type(current_expected):
-      return []
+    # Recursively search in children, in the case that the pattern also appears in children
+    for child in _get_children(current):
+      matches.extend(_search_tree(child, pattern))
     
-    if not hasattr(current, "tag"):
-      return [current] if current == current_expected else []
-    
-    _found = []
-    if _same(current, current_expected):
-      _found.append(current)
-    
-    # look at the children
-    for child in current.children:
-      _found.extend(_find(child, current_expected))
-    
-    return _found
+    return matches
   
-  ft_as_list = [ft] if not isinstance(ft, (list, tuple, set)) else ft
+  # Normalize input to list
+  elements_to_search = ft if isinstance(ft, (list, tuple, set)) else [ft]
   
-  for current_ft in ft_as_list:
-    found = _find(current_ft, expected)
-    res.extend(found)
+  # Search in all provided elements
+  all_matches = []
+  for element in elements_to_search:
+    all_matches.extend(_search_tree(element, expected))
   
-  if len(res) == 0:
+  # Raise error if nothing found
+  if not all_matches:
     raise AssertionError(f"No element found for '{expected}'")
   
-  return res
+  return all_matches
+
+
+def find_one(ft, expected):
+  found = find(ft, expected)
+  assert len(found) == 1, f"Found {len(found)} elements for '{expected}'"
+  return found[0]
+
+
+def _str_attrs(attrs: dict):
+  return " ".join(f'"{attr_name}"="{attr_value}"' for attr_name, attr_value in attrs.items())

tests/controls/conftest.py

@@ -1,6 +1,11 @@
 import pytest
 
-from myfasthtml.core.instances import SingleInstance
+from myfasthtml.core.instances import SingleInstance, InstancesManager
+
+
+class RootInstanceForTests(SingleInstance):
+  def __init__(self, session):
+    super().__init__(None, session, _id="TestRoot")
 
 
 @pytest.fixture(scope="session")
@@ -20,4 +25,5 @@ def session():
 
 @pytest.fixture(scope="session")
 def root_instance(session):
-  return SingleInstance(None, session, "TestRoot")
+  InstancesManager.reset()
+  return RootInstanceForTests(session=session)

tests/controls/test_layout.py

@@ -0,0 +1,677 @@
+"""Unit tests for Layout component."""
+import shutil
+
+import pytest
+from fasthtml.components import *
+
+from myfasthtml.controls.Layout import Layout
+from myfasthtml.controls.UserProfile import UserProfile
+from myfasthtml.test.matcher import matches, find, Contains, find_one, TestIcon, TestScript, TestObject, AnyValue, Skip, \
+  TestIconNotStr
+from .conftest import root_instance
+
+
+@pytest.fixture(autouse=True)
+def cleanup_db():
+  shutil.rmtree(".myFastHtmlDb", ignore_errors=True)
+
+
+class TestLayoutBehaviour:
+  """Tests for Layout behavior and logic."""
+  
+  def test_i_can_create_layout(self, root_instance):
+    """Test basic layout creation with app_name."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    assert layout is not None
+    assert layout.app_name == "Test App"
+    assert layout._state is not None
+  
+  def test_i_can_set_main_content(self, root_instance):
+    """Test setting main content area."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Main content")
+    
+    result = layout.set_main(content)
+    
+    assert layout._main_content == content
+    assert result == layout  # Should return self for chaining
+  
+  def test_i_can_add_content_to_left_drawer(self, root_instance):
+    """Test adding content to left drawer."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Left drawer content", id="drawer_item")
+    
+    layout.left_drawer.add(content)
+    
+    drawer_content = layout.left_drawer.get_content()
+    assert None in drawer_content
+    assert content in drawer_content[None]
+  
+  def test_i_can_add_content_to_right_drawer(self, root_instance):
+    """Test adding content to right drawer."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Right drawer content", id="drawer_item")
+    
+    layout.right_drawer.add(content)
+    
+    drawer_content = layout.right_drawer.get_content()
+    assert None in drawer_content
+    assert content in drawer_content[None]
+  
+  def test_i_can_add_content_to_header_left(self, root_instance):
+    """Test adding content to left side of header."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Header left content", id="header_item")
+    
+    layout.header_left.add(content)
+    
+    header_content = layout.header_left.get_content()
+    assert None in header_content
+    assert content in header_content[None]
+  
+  def test_i_can_add_content_to_header_right(self, root_instance):
+    """Test adding content to right side of header."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Header right content", id="header_item")
+    
+    layout.header_right.add(content)
+    
+    header_content = layout.header_right.get_content()
+    assert None in header_content
+    assert content in header_content[None]
+  
+  def test_i_can_add_grouped_content(self, root_instance):
+    """Test adding content with custom groups."""
+    layout = Layout(root_instance, app_name="Test App")
+    group_name = "navigation"
+    content1 = Div("Nav item 1", id="nav1")
+    content2 = Div("Nav item 2", id="nav2")
+    
+    layout.left_drawer.add(content1, group=group_name)
+    layout.left_drawer.add(content2, group=group_name)
+    
+    drawer_content = layout.left_drawer.get_content()
+    assert group_name in drawer_content
+    assert content1 in drawer_content[group_name]
+    assert content2 in drawer_content[group_name]
+  
+  def test_i_cannot_add_duplicate_content(self, root_instance):
+    """Test that content with same ID is not added twice."""
+    layout = Layout(root_instance, app_name="Test App")
+    content = Div("Content", id="unique_id")
+    
+    layout.left_drawer.add(content)
+    layout.left_drawer.add(content)  # Try to add again
+    
+    drawer_content = layout.left_drawer.get_content()
+    # Content should appear only once
+    assert drawer_content[None].count(content) == 1
+  
+  def test_i_can_toggle_left_drawer(self, root_instance):
+    """Test toggling left drawer open/closed."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    # Initially open
+    assert layout._state.left_drawer_open is True
+    
+    # Toggle to close
+    layout.toggle_drawer("left")
+    assert layout._state.left_drawer_open is False
+    
+    # Toggle to open
+    layout.toggle_drawer("left")
+    assert layout._state.left_drawer_open is True
+  
+  def test_i_can_toggle_right_drawer(self, root_instance):
+    """Test toggling right drawer open/closed."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    # Initially open
+    assert layout._state.right_drawer_open is True
+    
+    # Toggle to close
+    layout.toggle_drawer("right")
+    assert layout._state.right_drawer_open is False
+    
+    # Toggle to open
+    layout.toggle_drawer("right")
+    assert layout._state.right_drawer_open is True
+  
+  def test_i_can_update_left_drawer_width(self, root_instance):
+    """Test updating left drawer width."""
+    layout = Layout(root_instance, app_name="Test App")
+    new_width = 300
+    
+    layout.update_drawer_width("left", new_width)
+    
+    assert layout._state.left_drawer_width == new_width
+  
+  def test_i_can_update_right_drawer_width(self, root_instance):
+    """Test updating right drawer width."""
+    layout = Layout(root_instance, app_name="Test App")
+    new_width = 400
+    
+    layout.update_drawer_width("right", new_width)
+    
+    assert layout._state.right_drawer_width == new_width
+  
+  def test_i_cannot_set_drawer_width_below_minimum(self, root_instance):
+    """Test that drawer width is constrained to minimum 150px."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    layout.update_drawer_width("left", 100)  # Try to set below minimum
+    
+    assert layout._state.left_drawer_width == 150  # Should be clamped to min
+  
+  def test_i_cannot_set_drawer_width_above_maximum(self, root_instance):
+    """Test that drawer width is constrained to maximum 600px."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    layout.update_drawer_width("right", 800)  # Try to set above maximum
+    
+    assert layout._state.right_drawer_width == 600  # Should be clamped to max
+  
+  def test_i_cannot_toggle_invalid_drawer_side(self, root_instance):
+    """Test that toggling invalid drawer side raises ValueError."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    with pytest.raises(ValueError, match="Invalid drawer side"):
+      layout.toggle_drawer("invalid")
+  
+  def test_i_cannot_update_invalid_drawer_width(self, root_instance):
+    """Test that updating invalid drawer side raises ValueError."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    with pytest.raises(ValueError, match="Invalid drawer side"):
+      layout.update_drawer_width("invalid", 250)
+  
+  def test_layout_state_has_correct_defaults(self, root_instance):
+    """Test that LayoutState initializes with correct default values."""
+    layout = Layout(root_instance, app_name="Test App")
+    state = layout._state
+    
+    assert state.left_drawer_open is True
+    assert state.right_drawer_open is True
+    assert state.left_drawer_width == 250
+    assert state.right_drawer_width == 250
+  
+  def test_layout_is_single_instance(self, root_instance):
+    """Test that Layout behaves as SingleInstance (same ID returns same instance)."""
+    layout1 = Layout(root_instance, app_name="Test App", _id="my_layout")
+    layout2 = Layout(root_instance, app_name="Test App", _id="my_layout")
+    
+    # Should be the same instance
+    assert layout1 is layout2
+  
+  def test_commands_are_created(self, root_instance):
+    """Test that Layout creates necessary commands."""
+    layout = Layout(root_instance, app_name="Test App")
+    
+    # Test toggle commands
+    left_toggle_cmd = layout.commands.toggle_drawer("left")
+    assert left_toggle_cmd is not None
+    assert left_toggle_cmd.id is not None
+    
+    right_toggle_cmd = layout.commands.toggle_drawer("right")
+    assert right_toggle_cmd is not None
+    assert right_toggle_cmd.id is not None
+    
+    # Test width update commands
+    left_width_cmd = layout.commands.update_drawer_width("left")
+    assert left_width_cmd is not None
+    assert left_width_cmd.id is not None
+    
+    right_width_cmd = layout.commands.update_drawer_width("right")
+    assert right_width_cmd is not None
+    assert right_width_cmd.id is not None
+
+
+class TestLayoutRender:
+  """Tests for Layout HTML rendering."""
+  
+  @pytest.fixture
+  def layout(self, root_instance):
+    return Layout(root_instance, app_name="Test App")
+  
+  def test_empty_layout_is_rendered(self, layout):
+    """Test that Layout renders with all main structural sections.
+
+    Why these elements matter:
+    - 7 children: Verifies all main sections are rendered (tooltip container, header, drawers, main, footer, script)
+    - _id: Essential for layout identification and resizer initialization
+    - cls="mf-layout": Root CSS class for layout styling
+    """
+    expected = Div(
+      Div(),  # tooltip container
+      Header(),
+      Div(),  # left drawer
+      Main(),
+      Div(),  # right drawer
+      Footer(),
+      Script(),
+      _id=layout._id,
+      cls="mf-layout"
+    )
+    
+    assert matches(layout.render(), expected)
+  
+  def test_header_has_two_sides(self, layout):
+    """Test that there is a left and right header section."""
+    header = find_one(layout.render(), Header(cls="mf-layout-header"))
+    
+    expected = Header(
+      Div(id=f"{layout._id}_hl"),
+      Div(id=f"{layout._id}_hr"),
+    )
+    
+    assert matches(header, expected)
+  
+  def test_footer_has_two_sides(self, layout):
+    """Test that there is a left and right footer section."""
+    footer = find_one(layout.render(), Footer(cls=Contains("mf-layout-footer")))
+    
+    expected = Footer(
+      Div(id=f"{layout._id}_fl"),
+      Div(id=f"{layout._id}_fr"),
+    )
+    
+    assert matches(footer, expected)
+  
+  def test_header_with_drawer_icons_is_rendered(self, layout):
+    """Test that header renders with drawer toggle icons.
+
+    Why these elements matter:
+    - Only the first div is required to test the presence of the icon
+    - Use TestIcon to test the existence of an icon
+    """
+    header = find_one(layout.render(), Header(cls="mf-layout-header"))
+    
+    expected = Header(
+      Div(
+        TestIcon("PanelLeftContract20Regular"),
+        cls="flex gap-1"
+      ),
+      cls="mf-layout-header"
+    )
+    
+    assert matches(header, expected)
+  
+  def test_main_content_is_rendered_with_some_element(self, layout):
+    """Test that main content area renders correctly.
+
+    Why these elements matter:
+    - cls="mf-layout-main": Root main class for styling
+    """
+    layout.set_main(Div("Main content"))
+    main = find_one(layout.render(), Main(cls="mf-layout-main"))
+    
+    expected = Main(
+      Div("Main content"),
+      cls="mf-layout-main"
+    )
+    
+    assert matches(main, expected)
+  
+  def test_left_drawer_is_rendered_when_open(self, layout):
+    """Test that left drawer renders with correct classes when open.
+
+    Why these elements matter:
+    - _id: Required for targeting drawer in HTMX updates. search by id whenever possible
+    - cls Contains "mf-layout-drawer": Base drawer class for styling
+    - cls Contains "mf-layout-left-drawer": Left-specific drawer positioning
+    - style Contains width: Drawer width must be applied for sizing
+    """
+    layout._state.left_drawer_open = True
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+    
+    expected = Div(
+      _id=f"{layout._id}_ld",
+      cls=Contains("mf-layout-drawer", "mf-layout-left-drawer"),
+      style=Contains("width: 250px")
+    )
+    
+    assert matches(drawer, expected)
+  
+  def test_left_drawer_has_collapsed_class_when_closed(self, layout):
+    """Test that left drawer renders with collapsed class when closed.
+
+    Why these elements matter:
+    - _id: Required for targeting drawer in HTMX updates
+    - cls Contains "collapsed": Class triggers CSS hiding animation
+    - style Contains "width: 0px": Zero width is crucial for collapse animation
+    """
+    layout._state.left_drawer_open = False
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+    
+    expected = Div(
+      _id=f"{layout._id}_ld",
+      cls=Contains("mf-layout-drawer", "mf-layout-left-drawer", "collapsed"),
+      style=Contains("width: 0px")
+    )
+    
+    assert matches(drawer, expected)
+  
+  def test_right_drawer_is_rendered_when_open(self, layout):
+    """Test that right drawer renders with correct classes when open.
+
+    Why these elements matter:
+    - _id: Required for targeting drawer in HTMX updates
+    - cls Contains "mf-layout-drawer": Base drawer class for styling
+    - cls Contains "mf-layout-right-drawer": Right-specific drawer positioning
+    - style Contains width: Drawer width must be applied for sizing
+    """
+    layout._state.right_drawer_open = True
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_rd"))
+    
+    expected = Div(
+      _id=f"{layout._id}_rd",
+      cls=Contains("mf-layout-drawer", "mf-layout-right-drawer"),
+      style=Contains("width: 250px")
+    )
+    
+    assert matches(drawer, expected)
+  
+  def test_right_drawer_has_collapsed_class_when_closed(self, layout):
+    """Test that right drawer renders with collapsed class when closed.
+
+    Why these elements matter:
+    - _id: Required for targeting drawer in HTMX updates
+    - cls Contains "collapsed": Class triggers CSS hiding animation
+    - style Contains "width: 0px": Zero width is crucial for collapse animation
+    """
+    layout._state.right_drawer_open = False
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_rd"))
+    
+    expected = Div(
+      _id=f"{layout._id}_rd",
+      cls=Contains("mf-layout-drawer", "mf-layout-right-drawer", "collapsed"),
+      style=Contains("width: 0px")
+    )
+    
+    assert matches(drawer, expected)
+  
+  def test_drawer_width_is_applied_as_style(self, layout):
+    """Test that custom drawer width is applied as inline style.
+
+    Why this test matters:
+    - style Contains "width: 300px": Verifies that width updates are reflected in style attribute
+    """
+    layout._state.left_drawer_width = 300
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+    
+    expected = Div(
+      style=Contains("width: 300px")
+    )
+    
+    assert matches(drawer, expected)
+  
+  def test_left_drawer_has_resizer_element(self, layout):
+    """Test that left drawer contains resizer element.
+
+    Why this test matters:
+    - Resizer element must be present for drawer width adjustment
+    - cls "mf-resizer-left": Left-specific resizer for correct edge positioning
+    """
+    drawer = find(layout.render(), Div(id=f"{layout._id}_ld"))
+    resizers = find(drawer, Div(cls=Contains("mf-resizer-left")))
+    assert len(resizers) == 1, "Left drawer should contain exactly one resizer element"
+  
+  def test_right_drawer_has_resizer_element(self, layout):
+    """Test that right drawer contains resizer element.
+
+    Why this test matters:
+    - Resizer element must be present for drawer width adjustment
+    - cls "mf-resizer-right": Right-specific resizer for correct edge positioning
+    """
+    drawer = find(layout.render(), Div(id=f"{layout._id}_rd"))
+    resizers = find(drawer, Div(cls=Contains("mf-resizer-right")))
+    assert len(resizers) == 1, "Right drawer should contain exactly one resizer element"
+  
+  def test_resizer_script_is_included(self, layout):
+    """Test that resizer initialization script is included in render.
+
+    Why this test matters:
+    - Script element: Required to initialize resizer functionality
+    - Script contains initLayout call: Ensures layout is activated for this layout instance
+    """
+    script = find_one(layout.render(), Script())
+    expected = TestScript(f"initLayout('{layout._id}');")
+    
+    assert matches(script, expected)
+  
+  def test_left_drawer_renders_content_with_groups(self, layout):
+    """Test that left drawer renders content organized by groups with proper wrappers.
+
+    Why these elements matter:
+    - mf-layout-drawer-content wrapper: Required container for drawer scrolling behavior
+    - divider elements: Visual separation between content groups
+    - Group count validation: Ensures all added groups are rendered
+    """
+    layout.left_drawer.add(Div("Item 1", id="item1"), group="group1")
+    layout.left_drawer.add(Div("Item 2", id="item2"), group="group2")
+    
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+    
+    content_wrappers = find(drawer, Div(cls="mf-layout-drawer-content"))
+    assert len(content_wrappers) == 1, "Left drawer should contain exactly one content wrapper"
+    
+    content = content_wrappers[0]
+    dividers = find(content, Div(cls="divider"))
+    assert len(dividers) == 1, "Two groups should be separated by exactly one divider"
+  
+  
+  def test_header_left_renders_custom_content(self, layout):
+    """Test that custom content added to header_left is rendered in the left header section.
+
+    Why these elements matter:
+    - id="{layout._id}_hl": Essential for HTMX targeting during updates
+    - cls Contains "flex": Ensures horizontal layout of header items
+    - Icon presence: Toggle drawer icon must always be first element
+    - Custom content: Verifies header_left.add() correctly renders content
+    """
+    custom_content = Div("Custom Header", id="custom_header")
+    layout.header_left.add(custom_content)
+    
+    header_left = find_one(layout.render(), Div(id=f"{layout._id}_hl"))
+    
+    expected = Div(
+      TestIcon(""),
+      Skip(None),
+      Div("Custom Header", id="custom_header"),
+      id=f"{layout._id}_hl",
+      cls=Contains("flex", "gap-1")
+    )
+    
+    assert matches(header_left, expected)
+  
+  def test_header_right_renders_custom_content(self, layout):
+    """Test that custom content added to header_right is rendered in the right header section.
+
+    Why these elements matter:
+    - id="{layout._id}_hr": Essential for HTMX targeting during updates
+    - cls Contains "flex": Ensures horizontal layout of header items
+    - Custom content: Verifies header_right.add() correctly renders content
+    - UserProfile component: Must always be last element in right header
+    """
+    custom_content = Div("Custom Header Right", id="custom_header_right")
+    layout.header_right.add(custom_content)
+    
+    header_right = find_one(layout.render(), Div(id=f"{layout._id}_hr"))
+    
+    expected = Div(
+      Skip(None),
+      Div("Custom Header Right", id="custom_header_right"),
+      TestObject(UserProfile),
+      id=f"{layout._id}_hr",
+      cls=Contains("flex", "gap-1")
+    )
+    
+    assert matches(header_right, expected)
+  
+  def test_footer_left_renders_custom_content(self, layout):
+    """Test that custom content added to footer_left is rendered in the left footer section.
+
+    Why these elements matter:
+    - id="{layout._id}_fl": Essential for HTMX targeting during updates
+    - cls Contains "flex": Ensures horizontal layout of footer items
+    - Custom content: Verifies footer_left.add() correctly renders content
+    """
+    custom_content = Div("Custom Footer Left", id="custom_footer_left")
+    layout.footer_left.add(custom_content)
+    
+    footer_left = find_one(layout.render(), Div(id=f"{layout._id}_fl"))
+    
+    expected = Div(
+      Skip(None),
+      Div("Custom Footer Left", id="custom_footer_left"),
+      id=f"{layout._id}_fl",
+      cls=Contains("flex", "gap-1")
+    )
+    
+    assert matches(footer_left, expected)
+  
+  def test_footer_right_renders_custom_content(self, layout):
+    """Test that custom content added to footer_right is rendered in the right footer section.
+
+    Why these elements matter:
+    - id="{layout._id}_fr": Essential for HTMX targeting during updates
+    - cls Contains "flex": Ensures horizontal layout of footer items
+    - Custom content: Verifies footer_right.add() correctly renders content
+    """
+    custom_content = Div("Custom Footer Right", id="custom_footer_right")
+    layout.footer_right.add(custom_content)
+    
+    footer_right = find_one(layout.render(), Div(id=f"{layout._id}_fr"))
+    
+    expected = Div(
+      Skip(None),
+      Div("Custom Footer Right", id="custom_footer_right"),
+      id=f"{layout._id}_fr",
+      cls=Contains("flex", "gap-1")
+    )
+    
+    assert matches(footer_right, expected)
+  
+  def test_left_drawer_resizer_has_command_data(self, layout):
+    """Test that left drawer resizer has correct data attributes for command binding.
+
+    Why these elements matter:
+    - data_command_id: JavaScript uses this to trigger width update command
+    - data_side="left": JavaScript needs this to identify which drawer to resize
+    - cls Contains "mf-resizer-left": CSS uses this for left-specific positioning
+    """
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_ld"))
+    
+    resizer = find_one(drawer, Div(cls=Contains("mf-resizer-left")))
+    
+    expected = Div(
+      cls=Contains("mf-resizer", "mf-resizer-left"),
+      data_command_id=AnyValue(),
+      data_side="left"
+    )
+    
+    assert matches(resizer, expected)
+  
+  def test_right_drawer_resizer_has_command_data(self, layout):
+    """Test that right drawer resizer has correct data attributes for command binding.
+
+    Why these elements matter:
+    - data_command_id: JavaScript uses this to trigger width update command
+    - data_side="right": JavaScript needs this to identify which drawer to resize
+    - cls Contains "mf-resizer-right": CSS uses this for right-specific positioning
+    """
+    drawer = find_one(layout.render(), Div(id=f"{layout._id}_rd"))
+    
+    resizer = find_one(drawer, Div(cls=Contains("mf-resizer-right")))
+    
+    expected = Div(
+      cls=Contains("mf-resizer", "mf-resizer-right"),
+      data_command_id=AnyValue(),
+      data_side="right"
+    )
+    
+    assert matches(resizer, expected)
+  
+  def test_left_drawer_icon_changes_when_closed(self, layout):
+    """Test that left drawer toggle icon changes from expand to collapse when drawer is closed.
+
+    Why these elements matter:
+    - id="{layout._id}_ldi": Required for HTMX swap-oob updates when toggling
+    - Icon type: Visual feedback to user about drawer state (expand icon when closed)
+    - Icon change: Validates that toggle_drawer returns correct icon
+    """
+    layout._state.left_drawer_open = False
+    
+    icon_div = find_one(layout.render(), Div(id=f"{layout._id}_ldi"))
+    
+    expected = Div(
+      TestIconNotStr("panel_left_expand20_regular"),
+      id=f"{layout._id}_ldi"
+    )
+    
+    assert matches(icon_div, expected)
+  
+  def test_left_drawer_icon_changes_when_opne(self, layout):
+    """Test that left drawer toggle icon changes from collapse to expand when drawer is open..
+
+    Why these elements matter:
+    - id="{layout._id}_ldi": Required for HTMX swap-oob updates when toggling
+    - Icon type: Visual feedback to user about drawer state (expand icon when closed)
+    - Icon change: Validates that toggle_drawer returns correct icon
+    """
+    layout._state.left_drawer_open = True
+    
+    icon_div = find_one(layout.render(), Div(id=f"{layout._id}_ldi"))
+    
+    expected = Div(
+      TestIconNotStr("panel_left_contract20_regular"),
+      id=f"{layout._id}_ldi"
+    )
+    
+    assert matches(icon_div, expected)
+  
+  def test_tooltip_container_is_rendered(self, layout):
+    """Test that tooltip container is rendered at the top of the layout.
+
+    Why these elements matter:
+    - id="tt_{layout._id}": JavaScript uses this to append dynamically created tooltips
+    - cls Contains "mf-tooltip-container": CSS positioning for tooltip overlay layer
+    - Presence verification: Tooltips won't work if container is missing
+    """
+    tooltip_container = find_one(layout.render(), Div(id=f"tt_{layout._id}"))
+    
+    expected = Div(
+      id=f"tt_{layout._id}",
+      cls=Contains("mf-tooltip-container")
+    )
+    
+    assert matches(tooltip_container, expected)
+  
+  def test_header_right_contains_user_profile(self, layout):
+    """Test that UserProfile component is rendered in the right header section.
+
+    Why these elements matter:
+    - UserProfile component: Provides authentication and user menu functionality
+    - Position in header right: Conventional placement for user profile controls
+    - Count verification: Ensures component is not duplicated
+    """
+    header_right = find_one(layout.render(), Div(id=f"{layout._id}_hr"))
+    
+    user_profiles = find(header_right, TestObject(UserProfile))
+    
+    assert len(user_profiles) == 1, "Header right should contain exactly one UserProfile component"
+  
+  def test_layout_initialization_script_is_included(self, layout):
+    """Test that layout initialization script is included in render output.
+
+    Why these elements matter:
+    - Script presence: Required to initialize layout behavior (resizers, drawers)
+    - initLayout() call: Activates JavaScript functionality for this layout instance
+    - Layout ID parameter: Ensures initialization targets correct layout
+    """
+    script = find_one(layout.render(), Script())
+    
+    expected = TestScript(f"initLayout('{layout._id}');")
+    
+    assert matches(script, expected)

tests/controls/test_treeview.py

@@ -0,0 +1,860 @@
+"""Unit tests for TreeView component."""
+import shutil
+
+import pytest
+from fasthtml.components import *
+
+from myfasthtml.controls.Keyboard import Keyboard
+from myfasthtml.controls.TreeView import TreeView, TreeNode
+from myfasthtml.test.matcher import matches, TestObject, TestCommand, TestIcon, find_one, find, Contains, \
+  DoesNotContain
+from .conftest import root_instance
+
+
+@pytest.fixture(autouse=True)
+def cleanup_db():
+  shutil.rmtree(".myFastHtmlDb", ignore_errors=True)
+
+
+class TestTreeviewBehaviour:
+  """Tests for TreeView behavior and logic."""
+  
+  def test_i_can_create_tree_node_with_auto_generated_id(self):
+    """Test that TreeNode generates UUID automatically."""
+    node = TreeNode(label="Test Node", type="folder")
+    
+    assert node.id is not None
+    assert isinstance(node.id, str)
+    assert len(node.id) > 0
+  
+  def test_i_can_create_tree_node_with_default_values(self):
+    """Test that TreeNode has correct default values."""
+    node = TreeNode()
+    
+    assert node.label == ""
+    assert node.type == "default"
+    assert node.parent is None
+    assert node.children == []
+  
+  def test_i_can_initialize_tree_view_state(self, root_instance):
+    """Test that TreeViewState initializes with default values."""
+    tree_view = TreeView(root_instance)
+    state = tree_view._state
+    
+    assert isinstance(state.items, dict)
+    assert len(state.items) == 0
+    assert state.opened == []
+    assert state.selected is None
+    assert state.editing is None
+    assert state.icon_config == {}
+  
+  def test_i_can_create_empty_treeview(self, root_instance):
+    """Test creating an empty TreeView."""
+    tree_view = TreeView(root_instance)
+    
+    assert tree_view is not None
+    assert len(tree_view._state.items) == 0
+  
+  def test_i_can_add_node_to_treeview(self, root_instance):
+    """Test adding a root node to the TreeView."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Root Node", type="folder")
+    
+    tree_view.add_node(node)
+    
+    assert node.id in tree_view._state.items
+    assert tree_view._state.items[node.id].label == "Root Node"
+    assert tree_view._state.items[node.id].parent is None
+  
+  def test_i_can_add_child_node(self, root_instance):
+    """Test adding a child node to a parent."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    assert child.id in tree_view._state.items
+    assert child.id in parent.children
+    assert child.parent == parent.id
+  
+  def test_i_can_set_icon_config(self, root_instance):
+    """Test setting icon configuration."""
+    tree_view = TreeView(root_instance)
+    config = {
+        "folder": "fluent.folder",
+        "file": "fluent.document"
+    }
+    
+    tree_view.set_icon_config(config)
+    
+    assert tree_view._state.icon_config == config
+    assert tree_view._state.icon_config["folder"] == "fluent.folder"
+  
+  def test_i_can_toggle_node(self, root_instance):
+    """Test expand/collapse a node."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Node", type="folder")
+    tree_view.add_node(node)
+    
+    # Initially closed
+    assert node.id not in tree_view._state.opened
+    
+    # Toggle to open
+    tree_view._toggle_node(node.id)
+    assert node.id in tree_view._state.opened
+    
+    # Toggle to close
+    tree_view._toggle_node(node.id)
+    assert node.id not in tree_view._state.opened
+  
+  def test_i_can_expand_all_nodes(self, root_instance):
+    """Test that expand_all opens all nodes with children."""
+    tree_view = TreeView(root_instance)
+    
+    # Create hierarchy: root -> child1 -> grandchild
+    #                        -> child2 (leaf)
+    root = TreeNode(label="Root", type="folder")
+    child1 = TreeNode(label="Child 1", type="folder")
+    grandchild = TreeNode(label="Grandchild", type="file")
+    child2 = TreeNode(label="Child 2", type="file")
+    
+    tree_view.add_node(root)
+    tree_view.add_node(child1, parent_id=root.id)
+    tree_view.add_node(grandchild, parent_id=child1.id)
+    tree_view.add_node(child2, parent_id=root.id)
+    
+    # Initially all closed
+    assert len(tree_view._state.opened) == 0
+    
+    # Expand all
+    tree_view.expand_all()
+    
+    # Nodes with children should be opened
+    assert root.id in tree_view._state.opened
+    assert child1.id in tree_view._state.opened
+    
+    # Leaf nodes should not be in opened list
+    assert grandchild.id not in tree_view._state.opened
+    assert child2.id not in tree_view._state.opened
+  
+  def test_i_can_select_node(self, root_instance):
+    """Test selecting a node."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Node", type="folder")
+    tree_view.add_node(node)
+    
+    tree_view._select_node(node.id)
+    
+    assert tree_view._state.selected == node.id
+  
+  def test_i_can_start_rename_node(self, root_instance):
+    """Test starting rename mode for a node."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Old Name", type="folder")
+    tree_view.add_node(node)
+    
+    tree_view._start_rename(node.id)
+    
+    assert tree_view._state.editing == node.id
+  
+  def test_i_can_save_rename_node(self, root_instance):
+    """Test saving renamed node with new label."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Old Name", type="folder")
+    tree_view.add_node(node)
+    tree_view._start_rename(node.id)
+    
+    tree_view._save_rename(node.id, "New Name")
+    
+    assert tree_view._state.items[node.id].label == "New Name"
+    assert tree_view._state.editing is None
+  
+  def test_i_can_cancel_rename_node(self, root_instance):
+    """Test canceling rename operation."""
+    tree_view = TreeView(root_instance)
+    node = TreeNode(label="Name", type="folder")
+    tree_view.add_node(node)
+    tree_view._start_rename(node.id)
+    
+    tree_view._cancel_rename()
+    
+    assert tree_view._state.editing is None
+    assert tree_view._state.items[node.id].label == "Name"
+  
+  def test_i_can_delete_leaf_node(self, root_instance):
+    """Test deleting a node without children."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Delete child (leaf node)
+    tree_view._delete_node(child.id)
+    
+    assert child.id not in tree_view._state.items
+    assert child.id not in parent.children
+  
+  def test_i_can_add_sibling_node(self, root_instance):
+    """Test adding a sibling node."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child1 = TreeNode(label="Child 1", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child1, parent_id=parent.id)
+    
+    # Add sibling to child1
+    tree_view._add_sibling(child1.id, new_label="Child 2")
+    
+    assert len(parent.children) == 2
+    # Sibling should be after child1
+    assert parent.children.index(child1.id) < len(parent.children) - 1
+  
+  def test_i_cannot_delete_node_with_children(self, root_instance):
+    """Test that deleting a node with children raises an error."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Try to delete parent (has children)
+    with pytest.raises(ValueError, match="Cannot delete node.*with children"):
+      tree_view._delete_node(parent.id)
+  
+  def test_i_cannot_add_sibling_to_root(self, root_instance):
+    """Test that adding sibling to root node raises an error."""
+    tree_view = TreeView(root_instance)
+    root = TreeNode(label="Root", type="folder")
+    tree_view.add_node(root)
+    
+    # Try to add sibling to root (no parent)
+    with pytest.raises(ValueError, match="Cannot add sibling to root node"):
+      tree_view._add_sibling(root.id)
+  
+  def test_i_cannot_select_nonexistent_node(self, root_instance):
+    """Test that selecting a nonexistent node raises an error."""
+    tree_view = TreeView(root_instance)
+    
+    # Try to select node that doesn't exist
+    with pytest.raises(ValueError, match="Node.*does not exist"):
+      tree_view._select_node("nonexistent_id")
+  
+  def test_add_node_prevents_duplicate_children(self, root_instance):
+    """Test that add_node prevents adding duplicate child IDs."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Try to add the same child again
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Child should appear only once in parent's children list
+    assert parent.children.count(child.id) == 1
+  
+  def test_sibling_is_inserted_at_correct_position(self, root_instance):
+    """Test that _add_sibling inserts sibling exactly after reference node."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child1 = TreeNode(label="Child 1", type="file")
+    child3 = TreeNode(label="Child 3", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child1, parent_id=parent.id)
+    tree_view.add_node(child3, parent_id=parent.id)
+    
+    # Add sibling after child1
+    tree_view._add_sibling(child1.id, new_label="Child 2")
+    
+    # Get the newly added sibling
+    sibling_id = parent.children[1]
+    
+    # Verify order: child1, sibling (child2), child3
+    assert parent.children[0] == child1.id
+    assert tree_view._state.items[sibling_id].label == "Child 2"
+    assert parent.children[2] == child3.id
+    assert len(parent.children) == 3
+  
+  def test_add_child_auto_expands_parent(self, root_instance):
+    """Test that _add_child automatically expands the parent node."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    
+    tree_view.add_node(parent)
+    
+    # Parent should not be expanded initially
+    assert parent.id not in tree_view._state.opened
+    
+    # Add child
+    tree_view._add_child(parent.id, new_label="Child")
+    
+    # Parent should now be expanded
+    assert parent.id in tree_view._state.opened
+  
+  def test_i_cannot_add_child_to_nonexistent_parent(self, root_instance):
+    """Test that adding child to nonexistent parent raises error."""
+    tree_view = TreeView(root_instance)
+    
+    # Try to add child to parent that doesn't exist
+    with pytest.raises(ValueError, match="Parent node.*does not exist"):
+      tree_view._add_child("nonexistent_parent_id")
+  
+  def test_delete_node_clears_selection_if_selected(self, root_instance):
+    """Test that deleting a selected node clears the selection."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Select the child
+    tree_view._select_node(child.id)
+    assert tree_view._state.selected == child.id
+    
+    # Delete the selected child
+    tree_view._delete_node(child.id)
+    
+    # Selection should be cleared
+    assert tree_view._state.selected is None
+  
+  def test_delete_node_removes_from_opened_if_expanded(self, root_instance):
+    """Test that deleting an expanded node removes it from opened list."""
+    tree_view = TreeView(root_instance)
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Expand the parent
+    tree_view._toggle_node(parent.id)
+    assert parent.id in tree_view._state.opened
+    
+    # Delete the child (making parent a leaf)
+    tree_view._delete_node(child.id)
+    
+    # Now delete the parent (now a leaf node)
+    # First remove it from root by creating a grandparent
+    grandparent = TreeNode(label="Grandparent", type="folder")
+    tree_view.add_node(grandparent)
+    parent.parent = grandparent.id
+    grandparent.children.append(parent.id)
+    
+    tree_view._delete_node(parent.id)
+    
+    # Parent should be removed from opened list
+    assert parent.id not in tree_view._state.opened
+  
+  def test_i_cannot_start_rename_nonexistent_node(self, root_instance):
+    """Test that starting rename on nonexistent node raises error."""
+    tree_view = TreeView(root_instance)
+    
+    # Try to start rename on node that doesn't exist
+    with pytest.raises(ValueError, match="Node.*does not exist"):
+      tree_view._start_rename("nonexistent_id")
+  
+  def test_i_cannot_save_rename_nonexistent_node(self, root_instance):
+    """Test that saving rename for nonexistent node raises error."""
+    tree_view = TreeView(root_instance)
+    
+    # Try to save rename for node that doesn't exist
+    with pytest.raises(ValueError, match="Node.*does not exist"):
+      tree_view._save_rename("nonexistent_id", "New Name")
+  
+  def test_i_cannot_add_sibling_to_nonexistent_node(self, root_instance):
+    """Test that adding sibling to nonexistent node raises error."""
+    tree_view = TreeView(root_instance)
+    
+    # Try to add sibling to node that doesn't exist
+    with pytest.raises(ValueError, match="Node.*does not exist"):
+      tree_view._add_sibling("nonexistent_id")
+  
+  def test_i_can_initialize_with_items_dict(self, root_instance):
+    """Test that TreeView can be initialized with a dictionary of items."""
+    node1 = TreeNode(label="Node 1", type="folder")
+    node2 = TreeNode(label="Node 2", type="file")
+    
+    items = {node1.id: node1, node2.id: node2}
+    tree_view = TreeView(root_instance, items=items)
+    
+    assert len(tree_view._state.items) == 2
+    assert tree_view._state.items[node1.id].label == "Node 1"
+    assert tree_view._state.items[node1.id].type == "folder"
+    assert tree_view._state.items[node2.id].label == "Node 2"
+    assert tree_view._state.items[node2.id].type == "file"
+
+
+class TestTreeViewRender:
+  """Tests for TreeView HTML rendering."""
+  
+  @pytest.fixture
+  def tree_view(self, root_instance):
+    return TreeView(root_instance)
+  
+  def test_empty_treeview_is_rendered(self, tree_view):
+    """Test that empty TreeView generates correct HTML structure.
+
+    Why these elements matter:
+    - TestObject Keyboard: Essential for keyboard shortcuts (Escape to cancel rename)
+    - _id: Required for HTMX targeting and component identification
+    - cls "mf-treeview": Root CSS class for TreeView styling
+    """
+    expected = Div(
+      TestObject(Keyboard, combinations={"esc": TestCommand("CancelRename")}),
+      _id=tree_view.get_id(),
+      cls="mf-treeview"
+    )
+    
+    assert matches(tree_view.__ft__(), expected)
+  
+  def test_node_with_children_collapsed_is_rendered(self, tree_view):
+    """Test that a collapsed node with children renders correctly.
+
+    Why these elements matter:
+    - TestIcon chevron_right: Indicates visually that the node is collapsed
+    - Span with label: Displays the node's text content
+    - Action buttons (add_child, edit, delete): Enable user interactions
+    - cls "mf-treenode": Required CSS class for node styling
+    - data_node_id: Essential for identifying the node in DOM operations
+    - No children in container: Verifies children are hidden when collapsed
+    """
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Step 1: Extract the node element to test
+    rendered = tree_view.render()
+    
+    # Step 2: Define expected structure
+    expected = Div(
+      Div(
+        Div(
+          TestIcon("chevron_right20_regular"),  # Collapsed toggle icon
+          Span("Parent"),  # Label
+          Div(  # Action buttons
+            TestIcon("add_circle20_regular"),
+            TestIcon("edit20_regular"),
+            TestIcon("delete20_regular"),
+            cls=Contains("mf-treenode-actions")
+          ),
+          cls=Contains("mf-treenode"),
+        ),
+        cls="mf-treenode-container",
+        data_node_id=parent.id
+      ),
+      id=tree_view.get_id()
+    )
+    
+    # Step 3: Compare
+    assert matches(rendered, expected)
+    
+    # Verify no children are rendered (collapsed)
+    child_containers = find(rendered, Div(data_node_id=parent.id))
+    assert len(child_containers) == 1, "Children should not be rendered when node is collapsed"
+  
+  def test_node_with_children_expanded_is_rendered(self, tree_view):
+    """Test that an expanded node with children renders correctly.
+
+    Why these elements matter:
+    - TestIcon chevron_down: Indicates visually that the node is expanded
+    - Children rendered: Verifies that child nodes are visible when parent is expanded
+    - Child has its own node structure: Ensures recursive rendering works correctly
+    
+    Rendered Structure :
+    Div (node_container with data_node_id)
+      ├─ Div (information on current node - icon, label, actions)
+      └─ Div* (children - recursive containers, only if expanded)
+    """
+    parent = TreeNode(label="Parent", type="folder")
+    child1 = TreeNode(label="Child1", type="file")
+    child2 = TreeNode(label="Child2", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child1, parent_id=parent.id)
+    tree_view.add_node(child2, parent_id=parent.id)
+    tree_view._toggle_node(parent.id)  # Expand the parent
+    
+    # Step 1: Extract the parent node element to test
+    rendered = tree_view.render()
+    parent_container = find_one(rendered, Div(data_node_id=parent.id))
+    
+    expected = Div(
+      Div(),  # parent info (see test_node_with_children_collapsed_is_rendered)
+      Div(data_node_id=child1.id),
+      Div(data_node_id=child2.id),
+    )
+    
+    # Step 3: Compare
+    assert matches(parent_container, expected)
+    
+    # now check the child node structure
+    child_container = find_one(rendered, Div(data_node_id=child1.id))
+    expected_child_container = Div(
+      Div(
+        Div(None),  # No icon, the div is empty
+        Span("Child1"),
+        Div(),  # action buttons
+        cls=Contains("mf-treenode")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=child1.id,
+    )
+    assert matches(child_container, expected_child_container)
+  
+  def test_leaf_node_is_rendered(self, tree_view):
+    """Test that a leaf node (no children) renders without toggle icon.
+
+    Why these elements matter:
+    - No toggle icon (or empty space): Leaf nodes don't need expand/collapse functionality
+    - Span with label: Displays the node's text content
+    - Action buttons present: Even leaf nodes can be edited, deleted, or receive children
+    """
+    leaf = TreeNode(label="Leaf Node", type="file")
+    tree_view.add_node(leaf)
+    
+    # Step 1: Extract the leaf node element to test
+    rendered = tree_view.render()
+    leaf_container = find_one(rendered, Div(data_node_id=leaf.id))
+    
+    # Step 2: Define expected structure
+    expected = Div(
+      Div(
+        Div(None),  # No icon, the div is empty
+        Span("Leaf Node"),  # Label
+        Div(),  # Action buttons still present
+      ),
+      cls=Contains("mf-treenode"),
+      data_node_id=leaf.id
+    )
+    
+    # Step 3: Compare
+    assert matches(leaf_container, expected)
+  
+  def test_selected_node_has_selected_class(self, tree_view):
+    """Test that a selected node has the 'selected' CSS class.
+
+    Why these elements matter:
+    - cls Contains "selected": Enables visual highlighting of the selected node
+    - Div with mf-treenode: The node information container with selected class
+    - data_node_id: Required for identifying which node is selected
+    """
+    node = TreeNode(label="Selected Node", type="file")
+    tree_view.add_node(node)
+    tree_view._select_node(node.id)
+    
+    rendered = tree_view.render()
+    selected_container = find_one(rendered, Div(data_node_id=node.id))
+    
+    expected = Div(
+      Div(
+        Div(None),  # No icon, leaf node
+        Span("Selected Node"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode", "selected")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=node.id
+    )
+    
+    assert matches(selected_container, expected)
+  
+  def test_node_in_editing_mode_shows_input(self, tree_view):
+    """Test that a node in editing mode renders an Input instead of Span.
+
+    Why these elements matter:
+    - Input element: Enables user to modify the node label inline
+    - cls "mf-treenode-input": Required CSS class for input field styling
+    - name "node_label": Essential for form data submission
+    - value with current label: Pre-fills the input with existing text
+    - cls does NOT contain "selected": Avoids double highlighting during editing
+    """
+    node = TreeNode(label="Edit Me", type="file")
+    tree_view.add_node(node)
+    tree_view._start_rename(node.id)
+    
+    rendered = tree_view.render()
+    editing_container = find_one(rendered, Div(data_node_id=node.id))
+    
+    expected = Div(
+      Div(
+        Div(None),  # No icon, leaf node
+        Input(
+          name="node_label",
+          value="Edit Me",
+          cls=Contains("mf-treenode-input")
+        ),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=node.id
+    )
+    
+    assert matches(editing_container, expected)
+    
+    # Verify "selected" class is NOT present
+    editing_node_info = find_one(editing_container, Div(cls=Contains("mf-treenode", _word=True)))
+    no_selected = Div(
+      cls=DoesNotContain("selected")
+    )
+    assert matches(editing_node_info, no_selected)
+  
+  def test_node_indentation_increases_with_level(self, tree_view):
+    """Test that node indentation increases correctly with hierarchy level.
+
+    Why these elements matter:
+    - style Contains "padding-left: 0px": Root node has no indentation
+    - style Contains "padding-left: 20px": Child is indented by 20px
+    - style Contains "padding-left: 40px": Grandchild is indented by 40px
+    - Progressive padding: Creates the visual hierarchy of the tree structure
+    - Padding is applied to the node info Div, not the container
+    """
+    root = TreeNode(label="Root", type="folder")
+    child = TreeNode(label="Child", type="folder")
+    grandchild = TreeNode(label="Grandchild", type="file")
+    
+    tree_view.add_node(root)
+    tree_view.add_node(child, parent_id=root.id)
+    tree_view.add_node(grandchild, parent_id=child.id)
+    
+    # Expand all to make hierarchy visible
+    tree_view._toggle_node(root.id)
+    tree_view._toggle_node(child.id)
+    
+    rendered = tree_view.render()
+    
+    # Test root node (level 0)
+    root_container = find_one(rendered, Div(data_node_id=root.id))
+    root_expected = Div(
+      Div(
+        TestIcon("chevron_down20_regular"),  # Expanded icon
+        Span("Root"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode"),
+        style=Contains("padding-left: 0px")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=root.id
+    )
+    assert matches(root_container, root_expected)
+    
+    # Test child node (level 1)
+    child_container = find_one(rendered, Div(data_node_id=child.id))
+    child_expected = Div(
+      Div(
+        TestIcon("chevron_down20_regular"),  # Expanded icon
+        Span("Child"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode"),
+        style=Contains("padding-left: 20px")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=child.id
+    )
+    assert matches(child_container, child_expected)
+    
+    # Test grandchild node (level 2)
+    grandchild_container = find_one(rendered, Div(data_node_id=grandchild.id))
+    grandchild_expected = Div(
+      Div(
+        Div(None),  # No icon, leaf node
+        Span("Grandchild"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode"),
+        style=Contains("padding-left: 40px")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=grandchild.id
+    )
+    assert matches(grandchild_container, grandchild_expected)
+  
+  @pytest.mark.skip(reason="Not possible to validate if the command unicity is not fixed")
+  def test_toggle_icon_has_correct_command(self, tree_view):
+    """Test that toggle icon has ToggleNode command.
+
+    Why these elements matter:
+    - Div wrapper with command: mk.icon() wraps SVG in Div with HTMX attributes
+    - TestIcon inside Div: Verifies correct chevron icon is displayed
+    - TestCommand "ToggleNode": Essential for HTMX to route to correct handler
+    - Command targets correct node_id: Ensures the right node is toggled
+    """
+    parent = TreeNode(label="Parent", type="folder")
+    child = TreeNode(label="Child", type="file")
+    
+    tree_view.add_node(parent)
+    tree_view.add_node(child, parent_id=parent.id)
+    
+    # Step 1: Extract the parent node element
+    rendered = tree_view.render()
+    parent_node = find_one(rendered, Div(data_node_id=parent.id))
+    
+    # Step 2: Define expected structure
+    expected = Div(
+      Div(
+        TestIcon("chevron_right20_regular", command=tree_view.commands.toggle_node(parent.id)),
+      ),
+      data_node_id=parent.id
+    )
+    
+    # Step 3: Compare
+    assert matches(parent_node, expected)
+  
+  @pytest.mark.skip(reason="Not possible to validate if the command unicity is not fixed")
+  def test_action_buttons_have_correct_commands(self, tree_view):
+    """Test that action buttons have correct commands.
+
+    Why these elements matter:
+    - add_circle icon with AddChild: Enables adding child nodes via HTMX
+    - edit icon with StartRename: Triggers inline editing mode
+    - delete icon with DeleteNode: Enables node deletion
+    - cls "mf-treenode-actions": Required CSS class for button container styling
+    """
+    node = TreeNode(label="Node", type="folder")
+    tree_view.add_node(node)
+    
+    # Step 1: Extract the action buttons container
+    rendered = tree_view.render()
+    actions = find_one(rendered, Div(cls=Contains("mf-treenode-actions")))
+    
+    # Step 2: Define expected structure
+    expected = Div(
+      TestIcon("add_circle20_regular", command=tree_view.commands.add_child(node.id)),
+      TestIcon("edit20_regular", command=tree_view.commands.start_rename(node.id)),
+      TestIcon("delete20_regular", command=tree_view.commands.delete_node(node.id)),
+      cls=Contains("mf-treenode-actions")
+    )
+    
+    # Step 3: Compare
+    assert matches(actions, expected)
+  
+  @pytest.mark.skip(reason="Not possible to validate if the command unicity is not fixed")
+  def test_label_has_select_command(self, tree_view):
+    """Test that node label has SelectNode command.
+
+    Why these elements matter:
+    - Span with node label: Displays the node text
+    - TestCommand "SelectNode": Clicking label selects the node via HTMX
+    - cls "mf-treenode-label": Required CSS class for label styling
+    """
+    node = TreeNode(label="Clickable Node", type="file")
+    tree_view.add_node(node)
+    
+    # Step 1: Extract the label element
+    rendered = tree_view.render()
+    label = find_one(rendered, Span(cls=Contains("mf-treenode-label")))
+    
+    # Step 2: Define expected structure
+    expected = Span(
+      "Clickable Node",
+      command=tree_view.commands.select_node(node.id),
+      cls=Contains("mf-treenode-label")
+    )
+    
+    # Step 3: Compare
+    assert matches(label, expected)
+  
+  @pytest.mark.skip(reason="Not possible to validate if the command unicity is not fixed")
+  def test_input_has_save_rename_command(self, tree_view):
+    """Test that editing input has SaveRename command.
+
+    Why these elements matter:
+    - Input element: Enables inline editing of node label
+    - TestCommand "SaveRename": Submits new label via HTMX on form submission
+    - name "node_label": Required for form data to include the new label value
+    - value with current label: Pre-fills input with existing node text
+    """
+    node = TreeNode(label="Edit Me", type="file")
+    tree_view.add_node(node)
+    tree_view._start_rename(node.id)
+    
+    # Step 1: Extract the input element
+    rendered = tree_view.render()
+    input_elem = find_one(rendered, Input(name="node_label"))
+    
+    # Step 2: Define expected structure
+    expected = Input(
+      name="node_label",
+      value="Edit Me",
+      command=TestCommand(tree_view.commands.save_rename(node.id)),
+      cls=Contains("mf-treenode-input")
+    )
+    
+    # Step 3: Compare
+    assert matches(input_elem, expected)
+  
+  def test_keyboard_has_cancel_rename_command(self, tree_view):
+    """Test that Keyboard component has Escape key bound to CancelRename.
+
+    Why these elements matter:
+    - TestObject Keyboard: Verifies keyboard shortcuts component is present
+    - esc combination with CancelRename: Enables canceling rename with Escape key
+    - Essential for UX: Users expect Escape to cancel inline editing
+    """
+    # Step 1: Extract the Keyboard component
+    rendered = tree_view.render()
+    keyboard = find_one(rendered, TestObject(Keyboard))
+    
+    # Step 2: Define expected structure
+    expected = TestObject(Keyboard, combinations={"esc": TestCommand("CancelRename")})
+    
+    # Step 3: Compare
+    assert matches(keyboard, expected)
+
+  
+  def test_multiple_root_nodes_are_rendered(self, tree_view):
+    """Test that multiple root nodes are rendered at the same level.
+
+    Why these elements matter:
+    - Multiple root nodes: Verifies TreeView supports forest structure (multiple trees)
+    - All at same level: No artificial parent wrapping root nodes
+    - Each root has its own container: Proper structure for multiple independent trees
+    """
+    root1 = TreeNode(label="Root 1", type="folder")
+    root2 = TreeNode(label="Root 2", type="folder")
+
+    tree_view.add_node(root1)
+    tree_view.add_node(root2)
+
+    rendered = tree_view.render()
+    root_containers = find(rendered, Div(cls=Contains("mf-treenode-container")))
+
+    assert len(root_containers) == 2, "Should have two root-level containers"
+
+    root1_container = find_one(rendered, Div(data_node_id=root1.id))
+    root2_container = find_one(rendered, Div(data_node_id=root2.id))
+
+    expected_root1 = Div(
+      Div(
+        Div(None),  # No icon, leaf node
+        Span("Root 1"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=root1.id
+    )
+
+    expected_root2 = Div(
+      Div(
+        Div(None),  # No icon, leaf node
+        Span("Root 2"),
+        Div(),  # Action buttons
+        cls=Contains("mf-treenode")
+      ),
+      cls="mf-treenode-container",
+      data_node_id=root2.id
+    )
+
+    assert matches(root1_container, expected_root1)
+    assert matches(root2_container, expected_root2)

tests/html/keyboard_support.js

@@ -91,7 +91,6 @@
 
     for (const [combinationStr, config] of Object.entries(combinations)) {
       const sequence = parseCombination(combinationStr);
-      console.log("Parsing combination", combinationStr, "=>", sequence);
       let currentNode = root;
 
       for (const keySet of sequence) {

tests/testclient/test_finds.py

@@ -1,7 +1,22 @@
 import pytest
-from fasthtml.components import Div, Span
+from fastcore.basics import NotStr
+from fasthtml.components import Div, Span, Main
 
-from myfasthtml.test.matcher import find
+from myfasthtml.test.matcher import find, TestObject, Contains, StartsWith
+
+
+class Dummy:
+  def __init__(self, attr1, attr2=None):
+    self.attr1 = attr1
+    self.attr2 = attr2
+  
+  def __eq__(self, other):
+    return (isinstance(other, Dummy)
+            and self.attr1 == other.attr1
+            and self.attr2 == other.attr2)
+  
+  def __hash__(self):
+    return hash((self.attr1, self.attr2))
 
 
 @pytest.mark.parametrize('ft, expected', [
@@ -9,10 +24,13 @@ from myfasthtml.test.matcher import find
     (Div(id="id1"), Div(id="id1")),
     (Div(Span(id="span_id"), id="div_id1"), Div(Span(id="span_id"), id="div_id1")),
     (Div(id="id1", id2="id2"), Div(id="id1")),
-    (Div(Div(id="id2"), id2="id1"), Div(id="id1")),
+    (Div(Div(id="id2"), id="id1"), Div(id="id1")),
+    (Dummy(attr1="value"), Dummy(attr1="value")),
+    (Dummy(attr1="value"), TestObject(Dummy, attr1="value")),
+    (Div(attr="value1 value2"), Div(attr=Contains("value1"))),
 ])
 def test_i_can_find(ft, expected):
-  assert find(expected, expected) == [expected]
+  assert find(ft, expected) == [ft]
 
 
 def test_find_element_by_id_in_a_list():
@@ -25,12 +43,41 @@ def test_find_element_by_id_in_a_list():
 
 def test_i_can_find_sub_element():
   a = Div(id="id1")
-  b = Div(a, id="id2")
-  c = Div(b, id="id3")
+  b = Span(a, id="id2")
+  c = Main(b, id="id3")
   
   assert find(c, a) == [a]
 
 
+def test_i_can_find_when_pattern_appears_also_in_children():
+  a1 = Div(id="id1")
+  b = Div(a1, id="id2")
+  a2 = Div(b, id="id1")
+  c = Main(a2, id="id3")
+  
+  assert find(c, a1) == [a2, a1]
+
+
+@pytest.mark.parametrize('ft, to_search, expected', [
+    (NotStr("hello"), NotStr("hello"), [NotStr("hello")]),
+    (NotStr("hello my friend"), NotStr("hello"), NotStr("hello my friend")),
+    (NotStr("hello"), TestObject(NotStr, s="hello"), [NotStr("hello")]),
+    (NotStr("hello my friend"), TestObject(NotStr, s=StartsWith("hello")), NotStr("hello my friend")),
+])
+def test_i_can_manage_notstr_success_path(ft, to_search, expected):
+  assert find(ft, to_search) == expected
+
+
+@pytest.mark.parametrize('ft, to_search', [
+    (NotStr("my friend"), NotStr("hello")),
+    (NotStr("hello"), Dummy(attr1="hello")),  # important, because of the internal __eq__ of NotStr
+    (NotStr("hello my friend"), TestObject(NotStr, s="hello")),
+])
+def test_test_i_can_manage_notstr_failure_path(ft, to_search):
+  with pytest.raises(AssertionError):
+    find(ft, to_search)
+
+
 @pytest.mark.parametrize('ft, expected', [
     (None, Div(id="id1")),
     (Span(id="id1"), Div(id="id1")),

tests/testclient/test_matches.py

@@ -2,362 +2,469 @@ import pytest
 from fastcore.basics import NotStr
 from fasthtml.components import *
 
-from myfasthtml.test.matcher import matches, StartsWith, Contains, DoesNotContain, Empty, DoNotCheck, ErrorOutput, \
-  ErrorComparisonOutput, AttributeForbidden, AnyValue, NoChildren
+from myfasthtml.controls.helpers import mk
+from myfasthtml.core.commands import Command
+from myfasthtml.icons.fluent_p3 import add20_regular
+from myfasthtml.test.matcher import matches, StartsWith, Contains, DoesNotContain, Empty, ErrorOutput, \
+  ErrorComparisonOutput, AttributeForbidden, AnyValue, NoChildren, TestObject, Skip, DoNotCheck, TestIcon, HasHtmx
 from myfasthtml.test.testclient import MyFT
 
 
-@pytest.mark.parametrize('actual, expected', [
-    (None, None),
-    (123, 123),
-    (Div(), Div()),
-    ([Div(), Span()], [Div(), Span()]),
-    (Div(attr1="value"), Div(attr1="value")),
-    (Div(attr1="value", attr2="value"), Div(attr1="value")),
-    (Div(attr1="valueXXX", attr2="value"), Div(attr1=StartsWith("value"))),
-    (Div(attr1="before value after", attr2="value"), Div(attr1=Contains("value"))),
-    (Div(attr1="before after", attr2="value"), Div(attr1=DoesNotContain("value"))),
-    (Div(attr1="value"), Div(attr1=AnyValue())),
-    (None, DoNotCheck()),
-    (123, DoNotCheck()),
-    (Div(), DoNotCheck()),
-    ([Div(), Span()], DoNotCheck()),
-    (NotStr("123456"), NotStr("123")),  # for NotStr, only the beginning is checked
-    (Div(), Div(Empty())),
-    (Div(), Div(NoChildren())),
-    (Div(attr1="value"), Div(NoChildren())),
-    (Div(attr1="value1"), Div(AttributeForbidden("attr2"))),
-    (Div(123), Div(123)),
-    (Div(Span(123)), Div(Span(123))),
-    (Div(Span(123)), Div(DoNotCheck())),
-])
-def test_i_can_match(actual, expected):
-  assert matches(actual, expected)
+class Dummy:
+  def __init__(self, attr1, attr2=None):
+    self.attr1 = attr1
+    self.attr2 = attr2
 
 
-@pytest.mark.parametrize('actual, expected, error_message', [
-    (None, Div(), "Actual is None"),
-    (Div(), None, "Actual is not None"),
-    (123, Div(), "The types are different"),
-    (123, 124, "The values are different"),
-    ([Div(), Span()], [], "Actual is bigger than expected"),
-    ([], [Div(), Span()], "Actual is smaller than expected"),
-    ("not a list", [Div(), Span()], "The types are different"),
-    ([Div(), Span()], [Div(), 123], "The types are different"),
-    (Div(), Span(), "The elements are different"),
-    ([Div(), Span()], [Div(), Div()], "The elements are different"),
-    (Div(), Div(attr1="value"), "'attr1' is not found in Actual"),
-    (Div(attr2="value"), Div(attr1="value"), "'attr1' is not found in Actual"),
-    (Div(attr1="value1"), Div(attr1="value2"), "The values are different for 'attr1'"),
-    (Div(attr1="value1"), Div(attr1=StartsWith("value2")), "The condition 'StartsWith(value2)' is not satisfied"),
-    (Div(attr1="value1"), Div(attr1=Contains("value2")), "The condition 'Contains(value2)' is not satisfied"),
-    (Div(attr1="value1 value2"), Div(attr1=DoesNotContain("value2")), "The condition 'DoesNotContain(value2)'"),
-    (Div(attr1=None), Div(attr1=AnyValue()), "'attr1' is not found in Actual"),
-    (Div(), Div(attr1=AnyValue()), "'attr1' is not found in Actual"),
-    (NotStr("456"), NotStr("123"), "Notstr values are different"),
-    (Div(attr="value"), Div(Empty()), "The condition 'Empty()' is not satisfied"),
-    (Div(Span()), Div(NoChildren()), "The condition 'NoChildren()' is not satisfied"),
-    (Div(120), Div(Empty()), "The condition 'Empty()' is not satisfied"),
-    (Div(Span()), Div(Empty()), "The condition 'Empty()' is not satisfied"),
-    (Div(), Div(Span()), "Actual is lesser than expected"),
-    (Div(), Div(123), "Actual is lesser than expected"),
-    (Div(Span()), Div(Div()), "The elements are different"),
-    (Div(123), Div(Div()), "The types are different"),
-    (Div(123), Div(456), "The values are different"),
-    (Div(Span(), Span()), Div(Span(), Div()), "The elements are different"),
-    (Div(Span(Div())), Div(Span(Span())), "The elements are different"),
-    (Div(attr1="value1"), Div(AttributeForbidden("attr1")), "condition 'AttributeForbidden(attr1)' is not satisfied"),
-])
-def test_i_can_detect_errors(actual, expected, error_message):
-  with pytest.raises(AssertionError) as exc_info:
-    matches(actual, expected)
-  assert error_message in str(exc_info.value)
+class Dummy2:
+  def __init__(self, attr1, attr2):
+    self.attr1 = attr1
+    self.attr2 = attr2
 
 
-@pytest.mark.parametrize('element, expected_path', [
-    (Div(), "Path  : 'div"),
-    (Div(Span()), "Path  : 'div.span"),
-    (Div(Span(Div())), "Path  : 'div.span.div"),
-    (Div(id="div_id"), "Path  : 'div#div_id"),
-    (Div(cls="div_class"), "Path  : 'div[class=div_class]"),
-    (Div(name="div_class"), "Path  : 'div[name=div_class]"),
-    (Div(attr="value"), "Path  : 'div"),
-    (Div(Span(Div(), cls="span_class"), id="div_id"), "Path  : 'div#div_id.span[class=span_class].div"),
-])
-def test_i_can_properly_show_path(element, expected_path):
-  def _construct_test_element(source, tail):
-    res = MyFT(source.tag, source.attrs)
-    if source.children:
-      res.children = [_construct_test_element(child, tail) for child in source.children]
-    else:
-      res.children = [tail]
-    return res
+class TestMatches:
   
-  with pytest.raises(AssertionError) as exc_info:
-    actual = _construct_test_element(element, "Actual")
-    expected = _construct_test_element(element, "Expected")
-    matches(actual, expected)
+  @pytest.mark.parametrize('actual, expected', [
+      (None, None),
+      (123, 123),
+      (Div(), Div()),
+      ([Div(), Span()], [Div(), Span()]),
+      ({"key": Div(attr="value")}, {"key": Div(attr="value")}),
+      ({"key": Dummy(attr1="value")}, {"key": TestObject(Dummy, attr1="value")}),
+      (Div(attr1="value"), Div(attr1="value")),
+      (Div(attr1="value", attr2="value"), Div(attr1="value")),
+      (Div(attr1="valueXXX", attr2="value"), Div(attr1=StartsWith("value"))),
+      (Div(attr1="before value after", attr2="value"), Div(attr1=Contains("value"))),
+      (Div(attr1="before after", attr2="value"), Div(attr1=DoesNotContain("value"))),
+      (Div(attr1="value"), Div(attr1=AnyValue())),
+      (None, DoNotCheck()),
+      (123, DoNotCheck()),
+      (Div(), DoNotCheck()),
+      ([Div(), Span()], DoNotCheck()),
+      (NotStr("123456"), NotStr("123")),  # for NotStr, only the beginning is checked
+      (Div(), Div(Empty())),
+      (Div(), Div(NoChildren())),
+      (Div(attr1="value"), Div(NoChildren())),
+      (Div(attr1="value1"), Div(AttributeForbidden("attr2"))),
+      (Div(123), Div(123)),
+      (Div(Span(123)), Div(Span(123))),
+      (Div(Span(123)), Div(DoNotCheck())),
+      (Dummy(123, "value"), TestObject(Dummy, attr1=123, attr2="value")),
+      (Dummy(123, "value"), TestObject(Dummy, attr2="value")),
+      (Div(Dummy(123, "value")), Div(TestObject(Dummy, attr1=123))),
+      (Dummy(123, "value"), TestObject("Dummy", attr1=123, attr2="value")),
+      (mk.icon(add20_regular), TestIcon("Add20Regular")),
+      (mk.icon(add20_regular), TestIcon("add20_regular")),
+      (mk.icon(add20_regular), TestIcon()),
+      (Div(None, None, None, Div(id="to_find")), Div(Skip(None), Div(id="to_find"))),
+      (Div(Div(id="to_skip"), Div(id="to_skip"), Div(id="to_find")), Div(Skip(Div(id="to_skip")), Div(id="to_find"))),
+      (Div(hx_post="/url"), Div(HasHtmx(hx_post="/url"))),
+  ])
+  def test_i_can_match(self, actual, expected):
+    assert matches(actual, expected)
   
-  assert expected_path in str(exc_info.value)
-
-
-def test_i_can_output_error_path():
-  elt = Div()
-  expected = Div()
-  path = "div#div_id.div.span[class=span_class].p[name=p_name].div"
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "id"="div_id" ...',
-                                 '  (div ...',
-                                 '    (span "class"="span_class" ...',
-                                 '      (p "name"="p_name" ...',
-                                 '        (div )']
-
-
-def test_i_can_output_error_attribute():
-  elt = Div(attr1="value1", attr2="value2")
-  expected = elt
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1" "attr2"="value2")']
-
-
-def test_i_can_output_error_attribute_missing_1():
-  elt = Div(attr2="value2")
-  expected = Div(attr1="value1", attr2="value2")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="** MISSING **" "attr2"="value2")',
-                                 '     ^^^^^^^^^^^^^^^^^^^^^^^                 ']
-
-
-def test_i_can_output_error_attribute_missing_2():
-  elt = Div(attr1="value1")
-  expected = Div(attr1="value1", attr2="value2")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1" "attr2"="** MISSING **")',
-                                 '                      ^^^^^^^^^^^^^^^^^^^^^^^']
-
-
-def test_i_can_output_error_attribute_wrong_value():
-  elt = Div(attr1="value3", attr2="value2")
-  expected = Div(attr1="value1", attr2="value2")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value3" "attr2"="value2")',
-                                 '     ^^^^^^^^^^^^^^^^                 ']
-
-
-def test_i_can_output_error_constant():
-  elt = 123
-  expected = elt
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['123']
-
-
-def test_i_can_output_error_constant_wrong_value():
-  elt = 123
-  expected = 456
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['123',
-                                 '^^^']
-
-
-def test_i_can_output_error_when_predicate():
-  elt = "before value after"
-  expected = Contains("value")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ["before value after"]
-
-
-def test_i_can_output_error_when_predicate_wrong_value():
-  """I can display error when the condition predicate is not satisfied."""
-  elt = "before after"
-  expected = Contains("value")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ["before after",
-                                 "^^^^^^^^^^^^"]
-
-
-def test_i_can_output_error_child_element():
-  """I can display error when the element has children"""
-  elt = Div(P(id="p_id"), Div(id="child_1"), Div(id="child_2"), attr1="value1")
-  expected = elt
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1"',
-                                 '  (p "id"="p_id")',
-                                 '  (div "id"="child_1")',
-                                 '  (div "id"="child_2")',
-                                 ')',
-                                 ]
-
-
-def test_i_can_output_error_child_element_text():
-  """I can display error when the children is not a FT"""
-  elt = Div("Hello world", Div(id="child_1"), Div(id="child_2"), attr1="value1")
-  expected = elt
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1"',
-                                 '  "Hello world"',
-                                 '  (div "id"="child_1")',
-                                 '  (div "id"="child_2")',
-                                 ')',
-                                 ]
-
-
-def test_i_can_output_error_child_element_indicating_sub_children():
-  elt = Div(P(id="p_id"), Div(Div(id="child_2"), id="child_1"), attr1="value1")
-  expected = elt
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1"',
-                                 '  (p "id"="p_id")',
-                                 '  (div "id"="child_1" ...)',
-                                 ')',
-                                 ]
-
-
-def test_i_can_output_error_child_element_wrong_value():
-  elt = Div(P(id="p_id"), Div(id="child_2"), attr1="value1")
-  expected = Div(P(id="p_id"), Div(id="child_1"), attr1="value1")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1"',
-                                 '  (p "id"="p_id")',
-                                 '  (div "id"="child_2")',
-                                 '       ^^^^^^^^^^^^^^',
-                                 ')',
-                                 ]
-
-
-def test_i_can_output_error_fewer_elements():
-  elt = Div(P(id="p_id"), attr1="value1")
-  expected = Div(P(id="p_id"), Div(id="child_1"), attr1="value1")
-  path = ""
-  error_output = ErrorOutput(path, elt, expected)
-  error_output.compute()
-  assert error_output.output == ['(div "attr1"="value1"',
-                                 '  (p "id"="p_id")',
-                                 '  ! ** MISSING ** !',
-                                 ')',
-                                 ]
-
-
-def test_i_can_output_comparison():
-  actual = Div(P(id="p_id"), attr1="value1")
-  expected = actual
-  actual_out = ErrorOutput("", actual, expected)
-  expected_out = ErrorOutput("", expected, expected)
+  @pytest.mark.parametrize('actual, expected, error_message', [
+      (None, Div(), "Actual is None"),
+      (Div(), None, "Actual is not None"),
+      (123, Div(), "The types are different"),
+      (123, 124, "The values are different"),
+      ([Div(), Span()], [], "Actual is bigger than expected"),
+      ([], [Div(), Span()], "Actual is smaller than expected"),
+      ("not a list", [Div(), Span()], "The types are different"),
+      ([Div(), Span()], [Div(), 123], "The types are different"),
+      (Div(), Span(), "The types are different"),
+      ([Div(), Span()], [Div(), Div()], "The types are different"),
+      (Div(), Div(attr1="value"), "'attr1' is not found in Actual"),
+      (Div(attr2="value"), Div(attr1="value"), "'attr1' is not found in Actual"),
+      (Div(attr1="value1"), Div(attr1="value2"), "The values are different for 'attr1'"),
+      (Div(attr1="value1"), Div(attr1=StartsWith("value2")), "The condition 'StartsWith(value2)' is not satisfied"),
+      (Div(attr1="value1"), Div(attr1=Contains("value2")), "The condition 'Contains(value2)' is not satisfied"),
+      (Div(attr1="value1 value2"), Div(attr1=DoesNotContain("value2")), "The condition 'DoesNotContain(value2)'"),
+      (Div(attr1=None), Div(attr1=AnyValue()), "'attr1' is not found in Actual"),
+      (Div(), Div(attr1=AnyValue()), "'attr1' is not found in Actual"),
+      (NotStr("456"), NotStr("123"), "Notstr values are different"),
+      (Div(attr="value"), Div(Empty()), "The condition 'Empty()' is not satisfied"),
+      (Div(Span()), Div(NoChildren()), "The condition 'NoChildren()' is not satisfied"),
+      (Div(120), Div(Empty()), "The condition 'Empty()' is not satisfied"),
+      (Div(Span()), Div(Empty()), "The condition 'Empty()' is not satisfied"),
+      (Div(), Div(Span()), "Actual is lesser than expected"),
+      (Div(), Div(123), "Actual is lesser than expected"),
+      (Div(Span()), Div(Div()), "The types are different"),
+      (Div(123), Div(Div()), "The types are different"),
+      (Div(123), Div(456), "The values are different"),
+      (Div(Span(), Span()), Div(Span(), Div()), "The types are different"),
+      (Div(Span(Div())), Div(Span(Span())), "The types are different"),
+      (Div(attr1="value1"), Div(AttributeForbidden("attr1")), "condition 'AttributeForbidden(attr1)' is not satisfied"),
+      (Div(123, "value"), TestObject(Dummy, attr1=123, attr2="value2"), "The types are different"),
+      (Dummy(123, "value"), TestObject(Dummy, attr1=123, attr3="value3"), "'attr3' is not found in Actual"),
+      (Dummy(123, "value"), TestObject(Dummy, attr1=123, attr2="value2"), "The values are different for 'attr2'"),
+      (Div(Div(123, "value")), Div(TestObject(Dummy, attr1=123, attr2="value2")), "The types are different"),
+      (Div(Dummy(123, "value")), Div(TestObject(Dummy, attr1=123, attr3="value3")), "'attr3' is not found in Actual"),
+      (Div(Dummy(123, "value")), Div(TestObject(Dummy, attr1=123, attr2="value2")), "are different for 'attr2'"),
+      (Div(123, "value"), TestObject("Dummy", attr1=123, attr2="value2"), "The types are different"),
+      (Dummy(123, "value"), TestObject("Dummy", attr1=123, attr2=Contains("value2")),
+       "The condition 'Contains(value2)' is not satisfied"),
+      (Div(Div(id="to_skip")), Div(Skip(Div(id="to_skip"))), "Nothing more to skip"),
+      (Div(hx_post="/url"), Div(HasHtmx(hx_post="/url2")), "The condition 'HasHtmx()' is not satisfied"),
+  ])
+  def test_i_can_detect_errors(self, actual, expected, error_message):
+    with pytest.raises(AssertionError) as exc_info:
+      matches(actual, expected)
+    assert error_message in str(exc_info.value)
   
-  comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+  @pytest.mark.parametrize('element, expected_path', [
+      (Div(), "Path  : 'div"),
+      (Div(Span()), "Path  : 'div.span"),
+      (Div(Span(Div())), "Path  : 'div.span.div"),
+      (Div(id="div_id"), "Path  : 'div#div_id"),
+      (Div(cls="div_class"), "Path  : 'div[class=div_class]"),
+      (Div(name="div_class"), "Path  : 'div[name=div_class]"),
+      (Div(attr="value"), "Path  : 'div"),
+      (Div(Span(Div(), cls="span_class"), id="div_id"), "Path  : 'div#div_id.span[class=span_class].div"),
+  ])
+  def test_i_can_properly_show_path(self, element, expected_path):
+    def _construct_test_element(source, tail):
+      res = MyFT(source.tag, source.attrs)
+      if source.children:
+        res.children = [_construct_test_element(child, tail) for child in source.children]
+      else:
+        res.children = [tail]
+      return res
+    
+    with pytest.raises(AssertionError) as exc_info:
+      actual = _construct_test_element(element, "Actual")
+      expected = _construct_test_element(element, "Expected")
+      matches(actual, expected)
+    
+    assert expected_path in str(exc_info.value)
+
+
+class TestErrorOutput:
+  def test_i_can_output_error_path(self):
+    """The output follows the representation of the given path"""
+    elt = Div()
+    expected = Div()
+    path = "div#div_id.div.span[class=span_class].p[name=p_name].div"
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "id"="div_id" ...',
+                                   '  (div ...',
+                                   '    (span "class"="span_class" ...',
+                                   '      (p "name"="p_name" ...',
+                                   '        (div )']
   
-  res = comparison_out.render()
+  def test_i_can_output_error_attribute(self):
+    elt = Div(attr1="value1", attr2="value2")
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1" "attr2"="value2")']
   
-  assert "\n" + res == '''
+  def test_i_can_output_error_attribute_missing_1(self):
+    elt = Div(attr2="value2")
+    expected = Div(attr1="value1", attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="** MISSING **" "attr2"="value2")',
+                                   '     ^^^^^^^^^^^^^^^^^^^^^^^                 ']
+  
+  def test_i_can_output_error_attribute_missing_2(self):
+    elt = Div(attr1="value1")
+    expected = Div(attr1="value1", attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1" "attr2"="** MISSING **")',
+                                   '                      ^^^^^^^^^^^^^^^^^^^^^^^']
+  
+  def test_i_can_output_error_attribute_wrong_value(self):
+    elt = Div(attr1="value3", attr2="value2")
+    expected = Div(attr1="value1", attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value3" "attr2"="value2")',
+                                   '     ^^^^^^^^^^^^^^^^                 ']
+  
+  def test_i_can_output_error_constant(self):
+    elt = 123
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['123']
+  
+  def test_i_can_output_error_constant_wrong_value(self):
+    elt = 123
+    expected = 456
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['123',
+                                   '^^^']
+  
+  def test_i_can_output_error_when_predicate(self):
+    elt = "before value after"
+    expected = Contains("value")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ["before value after"]
+  
+  def test_i_can_output_error_when_predicate_wrong_value(self):
+    """I can display error when the condition predicate is not satisfied."""
+    elt = "before after"
+    expected = Contains("value")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ["before after",
+                                   "^^^^^^^^^^^^"]
+  
+  def test_i_can_output_error_child_element(self):
+    """I can display error when the element has children"""
+    elt = Div(P(id="p_id"), Div(id="child_1"), Div(id="child_2"), attr1="value1")
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1"',
+                                   '  (p "id"="p_id")',
+                                   '  (div "id"="child_1")',
+                                   '  (div "id"="child_2")',
+                                   ')',
+                                   ]
+  
+  def test_i_can_output_error_child_element_text(self):
+    """I can display error when the children is not a FT"""
+    elt = Div("Hello world", Div(id="child_1"), Div(id="child_2"), attr1="value1")
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1"',
+                                   '  "Hello world"',
+                                   '  (div "id"="child_1")',
+                                   '  (div "id"="child_2")',
+                                   ')',
+                                   ]
+  
+  def test_i_can_output_error_child_element_indicating_sub_children(self):
+    elt = Div(P(id="p_id"), Div(Div(id="child_2"), id="child_1"), attr1="value1")
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1"',
+                                   '  (p "id"="p_id")',
+                                   '  (div "id"="child_1" ...)',
+                                   ')',
+                                   ]
+  
+  def test_i_can_output_error_child_element_wrong_value(self):
+    elt = Div(P(id="p_id"), Div(id="child_2"), attr1="value1")
+    expected = Div(P(id="p_id"), Div(id="child_1"), attr1="value1")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1"',
+                                   '  (p "id"="p_id")',
+                                   '  (div "id"="child_2")',
+                                   '       ^^^^^^^^^^^^^^',
+                                   ')',
+                                   ]
+  
+  def test_i_can_output_error_fewer_elements(self):
+    elt = Div(P(id="p_id"), attr1="value1")
+    expected = Div(P(id="p_id"), Div(id="child_1"), attr1="value1")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(div "attr1"="value1"',
+                                   '  (p "id"="p_id")',
+                                   '  ! ** MISSING ** !',
+                                   ')',
+                                   ]
+  
+  def test_i_can_output_error_test_object(self):
+    elt = TestObject(Dummy, attr1=123, attr2="value2")
+    expected = elt
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == ['(Dummy "attr1"="123" "attr2"="value2")']
+  
+  def test_i_can_output_error_test_object_wrong_type(self):
+    elt = Div(attr1=123, attr2="value2")
+    expected = TestObject(Dummy, attr1=123, attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == [
+        '(div "attr1"="123" "attr2"="value2")',
+        ' ^^^                               '
+    ]
+  
+  def test_i_can_output_error_test_object_wrong_type_2(self):
+    elt = Dummy2(attr1=123, attr2="value2")
+    expected = TestObject(Dummy, attr1=123, attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == [
+        '(Dummy2 "attr1"="123" "attr2"="value2")',
+        ' ^^^^^^                               '
+    ]
+  
+  def test_i_can_output_error_test_object_wrong_type_3(self):
+    elt = Div(attr1=123, attr2="value2")
+    expected = TestObject("Dummy", attr1=123, attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == [
+        '(div "attr1"="123" "attr2"="value2")',
+        ' ^^^                               '
+    ]
+  
+  def test_i_can_output_error_test_object_wrong_value(self):
+    elt = Dummy(attr1="456", attr2="value2")
+    expected = TestObject(Dummy, attr1="123", attr2="value2")
+    path = ""
+    error_output = ErrorOutput(path, elt, expected)
+    error_output.compute()
+    assert error_output.output == [
+        '(Dummy "attr1"="456" "attr2"="value2")',
+        '       ^^^^^^^^^^^^^                 '
+    ]
+
+
+class TestErrorComparisonOutput:
+  def test_i_can_output_comparison(self):
+    actual = Div(P(id="p_id"), attr1="value1")
+    expected = actual
+    actual_out = ErrorOutput("", actual, expected)
+    expected_out = ErrorOutput("", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
 (div "attr1"="value1" | (div "attr1"="value1"
   (p "id"="p_id")     |   (p "id"="p_id")
 )                     | )'''
-
-
-def test_i_can_output_comparison_with_path():
-  actual = Div(P(id="p_id"), attr1="value1")
-  expected = actual
-  actual_out = ErrorOutput("div#div_id.span[class=cls].div", actual, expected)
-  expected_out = ErrorOutput("div#div_id.span[class=cls].div", expected, expected)
   
-  comparison_out = ErrorComparisonOutput(actual_out, expected_out)
-  
-  res = comparison_out.render()
-  
-  assert "\n" + res == '''
+  def test_i_can_output_comparison_with_path(self):
+    actual = Div(P(id="p_id"), attr1="value1")
+    expected = actual
+    actual_out = ErrorOutput("div#div_id.span[class=cls].div", actual, expected)
+    expected_out = ErrorOutput("div#div_id.span[class=cls].div", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
 (div "id"="div_id" ...    | (div "id"="div_id" ...
   (span "class"="cls" ... |   (span "class"="cls" ...
     (div "attr1"="value1" |     (div "attr1"="value1"
       (p "id"="p_id")     |       (p "id"="p_id")
     )                     |     )'''
-
-
-def test_i_can_output_comparison_when_missing_attributes():
-  actual = Div(P(id="p_id"), attr1="value1")
-  expected = Div(P(id="p_id"), attr2="value1")
-  actual_out = ErrorOutput("", actual, expected)
-  expected_out = ErrorOutput("", expected, expected)
   
-  comparison_out = ErrorComparisonOutput(actual_out, expected_out)
-  
-  res = comparison_out.render()
-  
-  assert "\n" + res == '''
+  def test_i_can_output_comparison_when_missing_attributes(self):
+    actual = Div(P(id="p_id"), attr1="value1")
+    expected = Div(P(id="p_id"), attr2="value1")
+    actual_out = ErrorOutput("", actual, expected)
+    expected_out = ErrorOutput("", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
 (div "attr2"="** MISSING **" | (div "attr2"="value1"
      ^^^^^^^^^^^^^^^^^^^^^^^ |
   (p "id"="p_id")            |   (p "id"="p_id")
 )                            | )'''
-
-
-def test_i_can_output_comparison_when_wrong_attributes():
-  actual = Div(P(id="p_id"), attr1="value2")
-  expected = Div(P(id="p_id"), attr1="value1")
-  actual_out = ErrorOutput("", actual, expected)
-  expected_out = ErrorOutput("", expected, expected)
   
-  comparison_out = ErrorComparisonOutput(actual_out, expected_out)
-  
-  res = comparison_out.render()
-  
-  assert "\n" + res == '''
+  def test_i_can_output_comparison_when_wrong_attributes(self):
+    actual = Div(P(id="p_id"), attr1="value2")
+    expected = Div(P(id="p_id"), attr1="value1")
+    actual_out = ErrorOutput("", actual, expected)
+    expected_out = ErrorOutput("", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
 (div "attr1"="value2" | (div "attr1"="value1"
      ^^^^^^^^^^^^^^^^ |
   (p "id"="p_id")     |   (p "id"="p_id")
 )                     | )'''
-
-
-def test_i_can_output_comparison_when_fewer_elements():
-  actual = Div(P(id="p_id"), attr1="value1")
-  expected = Div(Span(id="s_id"), P(id="p_id"), attr1="value1")
-  actual_out = ErrorOutput("", actual, expected)
-  expected_out = ErrorOutput("", expected, expected)
   
-  comparison_out = ErrorComparisonOutput(actual_out, expected_out)
-  
-  res = comparison_out.render()
-  
-  assert "\n" + res == '''
+  def test_i_can_output_comparison_when_fewer_elements(self):
+    actual = Div(P(id="p_id"), attr1="value1")
+    expected = Div(Span(id="s_id"), P(id="p_id"), attr1="value1")
+    actual_out = ErrorOutput("", actual, expected)
+    expected_out = ErrorOutput("", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
 (div "attr1"="value1" | (div "attr1"="value1"
   (p "id"="p_id")     |   (span "id"="s_id")
    ^ ^^^^^^^^^^^      |
   ! ** MISSING ** !   |   (p "id"="p_id")
 )                     | )'''
-
-
-def test_i_can_see_the_diff_when_matching():
-  actual = Div(attr1="value1")
-  expected = Div(attr1=Contains("value2"))
   
-  with pytest.raises(AssertionError) as exc_info:
-    matches(actual, expected)
-  
-  debug_output = str(exc_info.value)
-  assert "\n" + debug_output == """
+  def test_i_can_see_the_diff_when_matching(self):
+    actual = Div(attr1="value1")
+    expected = Div(attr1=Contains("value2"))
+    
+    with pytest.raises(AssertionError) as exc_info:
+      matches(actual, expected)
+    
+    debug_output = str(exc_info.value)
+    assert "\n" + debug_output == """
 Path  : 'div'
 Error : The condition 'Contains(value2)' is not satisfied.
 (div "attr1"="value1") | (div "attr1"="Contains(value2)")
      ^^^^^^^^^^^^^^^^  |"""
+  
+  def test_i_can_see_the_diff_with_test_object_when_wrong_type(self):
+    actual = Div(attr1=123, attr2="value2")
+    expected = TestObject(Dummy, attr1=123, attr2="value2")
+    
+    actual_out = ErrorOutput("dummy", actual, expected)
+    expected_out = ErrorOutput("div", expected, expected)
+    
+    comparison_out = ErrorComparisonOutput(actual_out, expected_out)
+    
+    res = comparison_out.render()
+    
+    assert "\n" + res == '''
+(div "attr1"="123" "attr2"="value2") | (Dummy "attr1"="123" "attr2"="value2")
+ ^^^                                 |'''
+
+
+class TestPredicates:
+  def test_i_can_validate_contains_with_words_only(self):
+    assert Contains("value", _word=True).validate("value value2 value3")
+    assert Contains("value", "value2", _word=True).validate("value value2 value3")
+    
+    assert not Contains("value", _word=True).validate("valuevalue2value3")
+    assert not Contains("value value2", _word=True).validate("value value2 value3")
+  
+  def test_i_can_validate_has_htmx(self):
+    div = Div(hx_post="/url")
+    assert HasHtmx(hx_post="/url").validate(div)
+    
+    c = Command("c", "testing has_htmx", None)
+    c.bind_ft(div)
+    assert HasHtmx(command=c).validate(div)