I can show and hide the columns comanger

.claude/commands/unit-tester.md

@@ -685,6 +685,56 @@ assert matches(element, expected)
 
 ---
 
+### UTR-16: Propose Parameterized Tests
+
+**Rule:** When proposing a test plan, systematically identify tests that can be parameterized and propose them as such.
+
+**When to parameterize:**
+- Tests that follow the same pattern with different input values
+- Tests that verify the same behavior for different sides/directions (left/right, up/down)
+- Tests that check the same logic with different states (visible/hidden, enabled/disabled)
+- Tests that validate the same method with different valid inputs
+
+**How to identify candidates:**
+1. Look for tests with similar names differing only by a value (e.g., `test_left_panel_...` and `test_right_panel_...`)
+2. Look for tests that have identical structure but different parameters
+3. Look for combinatorial scenarios (side × state combinations)
+
+**How to propose:**
+In your test plan, explicitly show:
+1. The individual tests that would be written without parameterization
+2. The parameterized version with all test cases
+3. The reduction in test count
+
+**Example proposal:**
+
+```
+**Without parameterization (4 tests):**
+- test_i_can_toggle_left_panel_from_visible_to_hidden
+- test_i_can_toggle_left_panel_from_hidden_to_visible
+- test_i_can_toggle_right_panel_from_visible_to_hidden
+- test_i_can_toggle_right_panel_from_hidden_to_visible
+
+**With parameterization (1 test, 4 cases):**
+@pytest.mark.parametrize("side, initial, expected", [
+    ("left", True, False),
+    ("left", False, True),
+    ("right", True, False),
+    ("right", False, True),
+])
+def test_i_can_toggle_panel_visibility(...)
+
+**Result:** 1 test instead of 4, same coverage
+```
+
+**Benefits:**
+- Reduces code duplication
+- Makes it easier to add new test cases
+- Improves maintainability
+- Makes the test matrix explicit
+
+---
+
 ## Managing Rules
 
 To disable a specific rule, the user can say:

docs/Panel.md

@@ -9,6 +9,7 @@ panels.
 **Key features:**
 
 - Three customizable zones (left panel, main content, right panel)
+- Configurable panel titles with sticky headers
 - Toggle visibility with hide/show icons
 - Resizable panels with drag handles
 - Smooth CSS animations for show/hide transitions
@@ -108,10 +109,37 @@ The Panel component consists of three zones with optional side panels:
 | Left panel    | Optional collapsible panel (default: visible) |
 | Main content  | Always-visible central content area           |
 | Right panel   | Optional collapsible panel (default: visible) |
-| Hide icon (−) | Inside each panel, top right corner           |
+| Hide icon (−) | Inside each panel header, right side          |
 | Show icon (⋯) | In main area when panel is hidden             |
 | Resizer (║)   | Drag handle to resize panels manually         |
 
+**Panel with title (default):**
+
+When `show_left_title` or `show_right_title` is `True` (default), panels display a sticky header with title and hide icon:
+
+```
+┌─────────────────────────────┐
+│ Title               [−]     │  ← Header (sticky, always visible)
+├─────────────────────────────┤
+│                             │
+│    Scrollable Content       │  ← Content area (scrolls independently)
+│                             │
+└─────────────────────────────┘
+```
+
+**Panel without title:**
+
+When `show_left_title` or `show_right_title` is `False`, panels use the legacy layout:
+
+```
+┌─────────────────────────────┐
+│                        [−]  │  ← Hide icon at top-right (absolute)
+│                             │
+│         Content             │
+│                             │
+└─────────────────────────────┘
+```
+
 ### Creating a Panel
 
 The Panel is a `MultipleInstance`, meaning you can create multiple independent panels in your application. Create it by
@@ -196,7 +224,7 @@ panel = Panel(parent=root_instance)
 
 ### Panel Configuration
 
-By default, both left and right panels are enabled. You can customize this with `PanelConf`:
+By default, both left and right panels are enabled with titles. You can customize this with `PanelConf`:
 
 ```python
 from myfasthtml.controls.Panel import PanelConf
@@ -218,6 +246,49 @@ conf = PanelConf(left=False, right=False)
 panel = Panel(parent=root_instance, conf=conf)
 ```
 
+**Customizing panel titles:**
+
+```python
+# Custom titles for panels
+conf = PanelConf(
+    left=True,
+    right=True,
+    left_title="Explorer",      # Custom title for left panel
+    right_title="Properties"    # Custom title for right panel
+)
+panel = Panel(parent=root_instance, conf=conf)
+```
+
+**Disabling panel titles:**
+
+When titles are disabled, panels use the legacy layout without a sticky header:
+
+```python
+# Disable titles (legacy layout)
+conf = PanelConf(
+    left=True,
+    right=True,
+    show_left_title=False,
+    show_right_title=False
+)
+panel = Panel(parent=root_instance, conf=conf)
+```
+
+**Disabling show icons:**
+
+You can hide the show icons (⋯) that appear when panels are hidden. This means users can only show panels programmatically:
+
+```python
+# Disable show icons (programmatic control only)
+conf = PanelConf(
+    left=True,
+    right=True,
+    show_display_left=False,   # No show icon for left panel
+    show_display_right=False   # No show icon for right panel
+)
+panel = Panel(parent=root_instance, conf=conf)
+```
+
 **Note:** When a panel is disabled in configuration, it won't render at all. When a panel is hidden (via toggle), it
 renders but with zero width and overflow hidden.
 
@@ -321,8 +392,8 @@ You can control panels programmatically using commands:
 
 ```python
 # Toggle panel visibility
-toggle_left = panel.commands.toggle_side("left", visible=False)  # Hide left
+toggle_left = panel.commands.set_side_visible("left", visible=False)  # Hide left
-toggle_right = panel.commands.toggle_side("right", visible=True)  # Show right
+toggle_right = panel.commands.set_side_visible("right", visible=True)  # Show right
 
 # Update panel width
 update_left_width = panel.commands.update_side_width("left")
@@ -335,8 +406,8 @@ These commands are typically used with buttons or other interactive elements:
 from myfasthtml.controls.helpers import mk
 
 # Add buttons to toggle panels
-hide_left_btn = mk.button("Hide Left", command=panel.commands.toggle_side("left", False))
+hide_left_btn = mk.button("Hide Left", command=panel.commands.set_side_visible("left", False))
-show_left_btn = mk.button("Show Left", command=panel.commands.toggle_side("left", True))
+show_left_btn = mk.button("Show Left", command=panel.commands.set_side_visible("left", True))
 
 # Add to your layout
 panel.set_main(
@@ -365,11 +436,15 @@ panel.set_main(
 The Panel uses CSS classes that you can customize:
 
 | Class                      | Element                                    |
-|----------------------------|------------------------------------------|
+|----------------------------|--------------------------------------------|
 | `mf-panel`                 | Root panel container                       |
 | `mf-panel-left`            | Left panel container                       |
 | `mf-panel-right`           | Right panel container                      |
 | `mf-panel-main`            | Main content area                          |
+| `mf-panel-with-title`      | Panel using title layout (no padding-top)  |
+| `mf-panel-body`            | Grid container for header + content        |
+| `mf-panel-header`          | Sticky header with title and hide icon     |
+| `mf-panel-content`         | Scrollable content area                    |
 | `mf-panel-hide-icon`       | Hide icon (−) inside panels                |
 | `mf-panel-show-icon`       | Show icon (⋯) in main area                 |
 | `mf-panel-show-icon-left`  | Show icon for left panel                   |
@@ -641,13 +716,13 @@ panel.set_right(
 # Create control buttons
 toggle_left_btn = mk.button(
   "Toggle Left Panel",
-  command=panel.commands.toggle_side("left", False),
+  command=panel.commands.set_side_visible("left", False),
   cls="btn btn-sm"
 )
 
 toggle_right_btn = mk.button(
   "Toggle Right Panel",
-  command=panel.commands.toggle_side("right", False),
+  command=panel.commands.set_side_visible("right", False),
   cls="btn btn-sm"
 )
 
@@ -697,9 +772,15 @@ This section contains technical details for developers working on the Panel comp
 The Panel component uses `PanelConf` dataclass for configuration:
 
 | Property             | Type    | Description                               | Default   |
-|----------|---------|----------------------------|---------|
+|----------------------|---------|-------------------------------------------|-----------|
-| `left`   | boolean | Enable/disable left panel  | `True`  |
+| `left`               | boolean | Enable/disable left panel                 | `False`   |
 | `right`              | boolean | Enable/disable right panel                | `True`    |
+| `left_title`         | string  | Title displayed in left panel header      | `"Left"`  |
+| `right_title`        | string  | Title displayed in right panel header     | `"Right"` |
+| `show_left_title`    | boolean | Show title header on left panel           | `True`    |
+| `show_right_title`   | boolean | Show title header on right panel          | `True`    |
+| `show_display_left`  | boolean | Show the "show" icon when left is hidden  | `True`    |
+| `show_display_right` | boolean | Show the "show" icon when right is hidden | `True`    |
 
 ### State
 
@@ -735,10 +816,40 @@ codebase.
 
 ### High Level Hierarchical Structure
 
+**With title (default, `show_*_title=True`):**
+
+```
+Div(id="{id}", cls="mf-panel")
+├── Div(id="{id}_pl", cls="mf-panel-left mf-panel-with-title [mf-hidden]")
+│   ├── Div(cls="mf-panel-body")
+│   │   ├── Div(cls="mf-panel-header")
+│   │   │   ├── Div [Title text]
+│   │   │   └── Div (hide icon)
+│   │   └── Div(id="{id}_cl", cls="mf-panel-content")
+│   │       └── [Left content - scrollable]
+│   └── Div (resizer-left)
+├── Div(cls="mf-panel-main")
+│   ├── Div(id="{id}_show_left", cls="hidden|mf-panel-show-icon-left")
+│   ├── Div(id="{id}_m", cls="mf-panel-main")
+│   │   └── [Main content]
+│   └── Div(id="{id}_show_right", cls="hidden|mf-panel-show-icon-right")
+├── Div(id="{id}_pr", cls="mf-panel-right mf-panel-with-title [mf-hidden]")
+│   ├── Div (resizer-right)
+│   └── Div(cls="mf-panel-body")
+│       ├── Div(cls="mf-panel-header")
+│       │   ├── Div [Title text]
+│       │   └── Div (hide icon)
+│       └── Div(id="{id}_cr", cls="mf-panel-content")
+│           └── [Right content - scrollable]
+└── Script  # initResizer('{id}')
+```
+
+**Without title (legacy, `show_*_title=False`):**
+
 ```
 Div(id="{id}", cls="mf-panel")
 ├── Div(id="{id}_pl", cls="mf-panel-left [mf-hidden]")
-│   ├── Div (hide icon)
+│   ├── Div (hide icon - absolute positioned)
 │   ├── Div(id="{id}_cl")
 │   │   └── [Left content]
 │   └── Div (resizer-left)
@@ -749,7 +860,7 @@ Div(id="{id}", cls="mf-panel")
 │   └── Div(id="{id}_show_right", cls="hidden|mf-panel-show-icon-right")
 ├── Div(id="{id}_pr", cls="mf-panel-right [mf-hidden]")
 │   ├── Div (resizer-right)
-│   ├── Div (hide icon)
+│   ├── Div (hide icon - absolute positioned)
 │   └── Div(id="{id}_cr")
 │       └── [Right content]
 └── Script  # initResizer('{id}')
@@ -757,11 +868,12 @@ Div(id="{id}", cls="mf-panel")
 
 **Note:**
 
-- Left panel: hide icon, then content, then resizer (resizer on right edge)
+- With title: uses grid layout (`mf-panel-body`) with sticky header and scrollable content
-- Right panel: resizer, then hide icon, then content (resizer on left edge)
+- Without title: hide icon is absolutely positioned at top-right with padding-top on panel
-- Hide icons are positioned at panel root level (not inside content div)
+- Left panel: body/content then resizer (resizer on right edge)
-- Main content has an outer wrapper and inner content div with ID
+- Right panel: resizer then body/content (resizer on left edge)
 - `[mf-hidden]` class is conditionally applied when panel is hidden
+- `mf-panel-with-title` class removes default padding-top when using title layout
 
 ### Element IDs
 

src/myfasthtml/assets/myfasthtml.css

@@ -459,7 +459,7 @@
 
 .mf-search-results {
     margin-top: 0.5rem;
-    max-height: 400px;
+    /*max-height: 400px;*/
     overflow: auto;
 }
 
@@ -769,6 +769,38 @@
     right: 0.5rem;
 }
 
+/* Panel with title - grid layout for header + scrollable content */
+.mf-panel-body {
+    display: grid;
+    grid-template-rows: auto 1fr;
+    height: 100%;
+    overflow: hidden;
+}
+
+.mf-panel-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 0.25rem 0.5rem;
+    background-color: var(--color-base-200);
+    border-bottom: 1px solid var(--color-border);
+}
+
+/* Override absolute positioning for hide icon when inside header */
+.mf-panel-header .mf-panel-hide-icon {
+    position: static;
+}
+
+.mf-panel-content {
+    overflow-y: auto;
+}
+
+/* Remove padding-top when using title layout */
+.mf-panel-left.mf-panel-with-title,
+.mf-panel-right.mf-panel-with-title {
+    padding-top: 0;
+}
+
 /* *********************************************** */
 /* ************* Properties Component ************ */
 /* *********************************************** */

src/myfasthtml/controls/DataGrid.py

@@ -14,7 +14,7 @@ from myfasthtml.controls.CycleStateControl import CycleStateControl
 from myfasthtml.controls.DataGridColumnsManager import DataGridColumnsManager
 from myfasthtml.controls.DataGridQuery import DataGridQuery, DG_QUERY_FILTER
 from myfasthtml.controls.Mouse import Mouse
-from myfasthtml.controls.Panel import Panel
+from myfasthtml.controls.Panel import Panel, PanelConf
 from myfasthtml.controls.datagrid_objects import DataGridColumnState, DataGridRowState, \
   DatagridSelectionState, DataGridHeaderFooterConf, DatagridEditionState
 from myfasthtml.controls.helpers import mk
@@ -26,6 +26,7 @@ from myfasthtml.core.optimized_ft import OptimizedDiv
 from myfasthtml.core.utils import make_safe_id
 from myfasthtml.icons.carbon import row, column, grid
 from myfasthtml.icons.fluent import checkbox_unchecked16_regular
+from myfasthtml.icons.fluent_p1 import settings16_regular
 from myfasthtml.icons.fluent_p2 import checkbox_checked16_regular
 
 # OPTIMIZATION: Pre-compiled regex to detect HTML special characters
@@ -130,6 +131,13 @@ class Commands(BaseCommands):
                    self._owner.on_click
                    ).htmx(target=f"#tsm_{self._id}")
   
+  def toggle_columns_manager(self):
+    return Command("ToggleColumnsManager",
+                   "Toggle Columns Manager",
+                   self._owner,
+                   self._owner.toggle_columns_manager
+                   ).htmx(target=None)
+
 
 class DataGrid(MultipleInstance):
   def __init__(self, parent, settings=None, save_state=None, _id=None):
@@ -139,7 +147,10 @@ class DataGrid(MultipleInstance):
     self.commands = Commands(self)
     self.init_from_dataframe(self._state.ne_df, init_state=False)  # state comes from DatagridState
     
-    self._panel = Panel(self, _id="-panel")
+    # add Panel
+    self._panel = Panel(self, conf=PanelConf(right_title="Columns", show_display_right=False), _id="-panel")
+    self._panel.set_side_visible("right", False)  # the right Panel always starts closed
+    self.bind_command("ToggleColumnsManager", self._panel.commands.toggle_side("right"))
     
     # add DataGridQuery
     self._datagrid_filter = DataGridQuery(self)
@@ -362,6 +373,10 @@ class DataGrid(MultipleInstance):
     self._state.save()
     return self.render_partial()
   
+  def toggle_columns_manager(self):
+    logger.debug(f"toggle_columns_manager")
+    self._panel.set_right(self._columns_manager)
+  
   def mk_headers(self):
     resize_cmd = self.commands.set_column_width()
     move_cmd = self.commands.move_column()
@@ -649,7 +664,7 @@ class DataGrid(MultipleInstance):
       Div(self._datagrid_filter,
           Div(
             self._selection_mode_selector,
-            self._columns_manager,
+            mk.icon(settings16_regular, command=self.commands.toggle_columns_manager(), tooltip="Show sidebar"),
             cls="flex"),
           cls="flex items-center justify-between mb-2"),
       self._panel.set_main(self.mk_table()),

src/myfasthtml/controls/DataGridColumnsManager.py

@@ -1,17 +1,17 @@
 from fasthtml.components import *
 
-from myfasthtml.controls.Dropdown import Dropdown
 from myfasthtml.controls.Search import Search
 from myfasthtml.controls.datagrid_objects import DataGridColumnState
-from myfasthtml.controls.helpers import mk
+from myfasthtml.core.instances import MultipleInstance
-from myfasthtml.icons.fluent_p1 import settings16_regular
 
 
-class DataGridColumnsManager(Dropdown):
+class DataGridColumnsManager(MultipleInstance):
   def __init__(self, parent, _id=None):
-    super().__init__(parent, _id=_id, align="right")
+    super().__init__(parent, _id=_id)
-    self.button = mk.icon(settings16_regular)
+  
-    self.content = self.create_content()
+  @property
+  def columns(self):
+    return self._parent._state.columns
   
   def mk_column(self, col_def: DataGridColumnState):
     return Div(
@@ -20,14 +20,14 @@ class DataGridColumnsManager(Dropdown):
       cls="flex mb-1",
     )
   
-  def create_content(self):
+  def render(self):
     return Search(self,
                   items_names="Columns",
                   items=self.columns,
                   get_attr=lambda x: x.col_id,
-                  template=self.mk_column
+                  template=self.mk_column,
+                  max_height=None
                   )
   
-  @property
+  def __ft__(self):
-  def columns(self):
+    return self.render()
-    return self._parent._state.columns

src/myfasthtml/controls/Panel.py

@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from typing import Literal
+from typing import Literal, Optional
 
 from fasthtml.components import Div
 from fasthtml.xtend import Script
@@ -42,6 +42,12 @@ class PanelIds:
 class PanelConf:
   left: bool = False
   right: bool = True
+  left_title: str = "Left"
+  right_title: str = "Right"
+  show_left_title: bool = True
+  show_right_title: bool = True
+  show_display_left: bool = True
+  show_display_right: bool = True
 
 
 class PanelState(DbObject):
@@ -55,12 +61,19 @@ class PanelState(DbObject):
 
 
 class Commands(BaseCommands):
-  def toggle_side(self, side: Literal["left", "right"], visible: bool = None):
+  def set_side_visible(self, side: Literal["left", "right"], visible: bool = None):
+    return Command("TogglePanelSide",
+                   f"Toggle {side} side panel",
+                   self._owner,
+                   self._owner.set_side_visible,
+                   args=[side, visible]).htmx(target=f"#{self._owner.get_ids().panel(side)}")
+  
+  def toggle_side(self, side: Literal["left", "right"]):
     return Command("TogglePanelSide",
                    f"Toggle {side} side panel",
                    self._owner,
                    self._owner.toggle_side,
-                   args=[side, visible]).htmx(target=f"#{self._owner.get_ids().panel(side)}")
+                   args=[side]).htmx(target=f"#{self._owner.get_ids().panel(side)}")
   
   def update_side_width(self, side: Literal["left", "right"]):
     """
@@ -89,7 +102,7 @@ class Panel(MultipleInstance):
   the panel with appropriate HTML elements and JavaScript for interactivity.
   """
   
-  def __init__(self, parent, conf=None, _id=None):
+  def __init__(self, parent, conf: Optional[PanelConf] = None, _id=None):
     super().__init__(parent, _id=_id)
     self.conf = conf or PanelConf()
     self.commands = Commands(self)
@@ -110,7 +123,7 @@ class Panel(MultipleInstance):
     
     return self._mk_panel(side)
   
-  def toggle_side(self, side, visible):
+  def set_side_visible(self, side, visible):
     if side == "left":
       self._state.left_visible = visible
     else:
@@ -118,6 +131,10 @@ class Panel(MultipleInstance):
     
     return self._mk_panel(side), self._mk_show_icon(side)
   
+  def toggle_side(self, side):
+    current_visible = self._state.left_visible if side == "left" else self._state.right_visible
+    return self.set_side_visible(side, not current_visible)
+  
   def set_main(self, main):
     self._main = main
     return self
@@ -137,6 +154,8 @@ class Panel(MultipleInstance):
 
     visible = self._state.left_visible if side == "left" else self._state.right_visible
     content = self._right if side == "right" else self._left
+    show_title = self.conf.show_left_title if side == "left" else self.conf.show_right_title
+    title = self.conf.left_title if side == "left" else self.conf.right_title
 
     resizer = Div(
       cls=f"mf-resizer mf-resizer-{side}",
@@ -147,16 +166,44 @@ class Panel(MultipleInstance):
     hide_icon = mk.icon(
       subtract20_regular,
       size=20,
-      command=self.commands.toggle_side(side, False),
+      command=self.commands.set_side_visible(side, False),
       cls="mf-panel-hide-icon"
     )
 
     panel_cls = f"mf-panel-{side}"
     if not visible:
       panel_cls += " mf-hidden"
+    if show_title:
+      panel_cls += " mf-panel-with-title"
 
     # Left panel: content then resizer (resizer on the right)
     # Right panel: resizer then content (resizer on the left)
+    if show_title:
+      header = Div(
+        Div(title),
+        hide_icon,
+        cls="mf-panel-header"
+      )
+      body = Div(
+        header,
+        Div(content, id=self._ids.content(side), cls="mf-panel-content"),
+        cls="mf-panel-body"
+      )
+      if side == "left":
+        return Div(
+          body,
+          resizer,
+          cls=panel_cls,
+          id=self._ids.panel(side)
+        )
+      else:
+        return Div(
+          resizer,
+          body,
+          cls=panel_cls,
+          id=self._ids.panel(side)
+        )
+    else:
       if side == "left":
         return Div(
           hide_icon,
@@ -196,12 +243,16 @@ class Panel(MultipleInstance):
     if not enabled:
       return None
 
+    show_display = self.conf.show_display_left if side == "left" else self.conf.show_display_right
+    if not show_display:
+      return None
+
     is_visible = self._state.left_visible if side == "left" else self._state.right_visible
     icon_cls = "hidden" if is_visible else f"mf-panel-show-icon mf-panel-show-icon-{side}"
 
     return mk.icon(
       more_horizontal20_regular,
-      command=self.commands.toggle_side(side, True),
+      command=self.commands.set_side_visible(side, True),
       cls=icon_cls,
       id=f"{self._id}_show_{side}"
     )

src/myfasthtml/controls/Search.py

@@ -45,7 +45,8 @@ class Search(MultipleInstance):
                items_names=None,  # what is the name of the items to filter
                items=None,  # first set of items to filter
                get_attr: Callable[[Any], str] = None,  # items is  a list of objects: how to  get the str to filter
-               template: Callable[[Any], Any] = None):  # once filtered, what to render ?
+               template: Callable[[Any], Any] = None,  # once filtered, what to render ?
+               max_height: int = 400):
     """
     Represents a component for managing and filtering a list of items based on specific criteria.
 
@@ -66,6 +67,7 @@ class Search(MultipleInstance):
     self.get_attr = get_attr or (lambda x: x)
     self.template = template or (lambda x: Div(self.get_attr(x)))
     self.commands = Commands(self)
+    self.max_height = max_height
   
   def set_items(self, items):
     self.items = items
@@ -106,6 +108,7 @@ class Search(MultipleInstance):
         *self._mk_search_results(),
         id=f"{self._id}-results",
         cls="mf-search-results",
+        style="max-height: 400px;" if self.max_height else None
       ),
       id=f"{self._id}",
     )

tests/controls/test_panel.py

@@ -96,7 +96,7 @@ class TestPanelBehaviour:
     """Test that toggle_side('left', False) sets _state.left_visible to False."""
     panel = Panel(root_instance)
     
-    panel.toggle_side("left", False)
+    panel.set_side_visible("left", False)
     
     assert panel._state.left_visible is False
   
@@ -105,7 +105,7 @@ class TestPanelBehaviour:
     panel = Panel(root_instance)
     panel._state.left_visible = False
     
-    panel.toggle_side("left", True)
+    panel.set_side_visible("left", True)
     
     assert panel._state.left_visible is True
   
@@ -113,7 +113,7 @@ class TestPanelBehaviour:
     """Test that toggle_side('right', False) sets _state.right_visible to False."""
     panel = Panel(root_instance)
     
-    panel.toggle_side("right", False)
+    panel.set_side_visible("right", False)
     
     assert panel._state.right_visible is False
   
@@ -122,15 +122,45 @@ class TestPanelBehaviour:
     panel = Panel(root_instance)
     panel._state.right_visible = False
     
-    panel.toggle_side("right", True)
+    panel.set_side_visible("right", True)
     
     assert panel._state.right_visible is True
   
+  def test_set_side_visible_returns_panel_and_icon(self, root_instance):
+    """Test that set_side_visible() returns a tuple (panel_element, show_icon_element)."""
+    panel = Panel(root_instance)
+    
+    result = panel.set_side_visible("left", False)
+    
+    assert isinstance(result, tuple)
+    assert len(result) == 2
+  
+  @pytest.mark.parametrize("side, initial_visible, expected_visible", [
+      ("left", True, False),  # left visible → hidden
+      ("left", False, True),  # left hidden → visible
+      ("right", True, False),  # right visible → hidden
+      ("right", False, True),  # right hidden → visible
+  ])
+  def test_i_can_toggle_panel_visibility(self, root_instance, side, initial_visible, expected_visible):
+    """Test that toggle_side() inverts the visibility state."""
+    panel = Panel(root_instance)
+    if side == "left":
+      panel._state.left_visible = initial_visible
+    else:
+      panel._state.right_visible = initial_visible
+    
+    panel.toggle_side(side)
+    
+    if side == "left":
+      assert panel._state.left_visible is expected_visible
+    else:
+      assert panel._state.right_visible is expected_visible
+  
   def test_toggle_side_returns_panel_and_icon(self, root_instance):
     """Test that toggle_side() returns a tuple (panel_element, show_icon_element)."""
     panel = Panel(root_instance)
     
-    result = panel.toggle_side("left", False)
+    result = panel.toggle_side("left")
     
     assert isinstance(result, tuple)
     assert len(result) == 2
@@ -190,13 +220,39 @@ class TestPanelBehaviour:
     
     assert result is None
   
+  @pytest.mark.parametrize("side, conf_kwargs", [
+      ("left", {"show_display_left": False}),
+      ("right", {"show_display_right": False}),
+  ])
+  def test_show_icon_returns_none_when_show_display_disabled(self, root_instance, side, conf_kwargs):
+    """Test that _mk_show_icon() returns None when show_display is disabled."""
+    custom_conf = PanelConf(left=True, right=True, **conf_kwargs)
+    panel = Panel(root_instance, conf=custom_conf)
+    
+    result = panel._mk_show_icon(side)
+    
+    assert result is None
+
 
 class TestPanelRender:
   """Tests for Panel HTML rendering."""
   
   @pytest.fixture
   def panel(self, root_instance):
-    panel = Panel(root_instance, PanelConf(True, True))
+    """Panel with titles (default behavior)."""
+    panel = Panel(root_instance, PanelConf(left=True, right=True))
+    panel.set_main(Div("Main content"))
+    panel.set_left(Div("Left content"))
+    panel.set_right(Div("Right content"))
+    return panel
+  
+  @pytest.fixture
+  def panel_no_title(self, root_instance):
+    """Panel without titles (legacy behavior)."""
+    panel = Panel(root_instance, PanelConf(
+      left=True, right=True,
+      show_left_title=False, show_right_title=False
+    ))
     panel.set_main(Div("Main content"))
     panel.set_left(Div("Left content"))
     panel.set_right(Div("Right content"))
@@ -225,22 +281,58 @@ class TestPanelRender:
   
   # 2. Left panel
   
-  def test_left_panel_renders_with_correct_structure(self, panel):
+  def test_left_panel_renders_with_title_structure(self, panel):
-    """Test that left panel has content div before resizer.
+    """Test that left panel with title has header + scrollable content.
 
     Why these elements matter:
-    - Order (content then resizer): Critical for positioning resizer on the right side
+    - mf-panel-body: Grid container for header + content layout
-    - id: Required for HTMX targeting during toggle/resize operations
+    - mf-panel-header: Contains title and hide icon
-    - cls Contains "mf-panel-left": CSS class for left panel styling
+    - mf-panel-content: Scrollable content area
+    - mf-panel-with-title: Removes default padding-top
     """
     left_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("left")))
     
-    # Step 1: Validate left panel global structure
     expected = Div(
-      TestIcon("subtract20_regular"),
+      Div(cls=Contains("mf-panel-body")),  # body with header + content
-      Div(id=panel.get_ids().left),  # content div, tested in detail later
       Div(cls=Contains("mf-resizer-left")),  # resizer
       id=panel.get_ids().panel("left"),
+      cls=Contains("mf-panel-left", "mf-panel-with-title")
+    )
+    
+    assert matches(left_panel, expected)
+  
+  def test_left_panel_header_contains_title_and_icon(self, panel):
+    """Test that left panel header has title and hide icon.
+
+    Why these elements matter:
+    - Title: Displays the panel title (left aligned)
+    - Hide icon: Allows user to collapse the panel (right aligned)
+    """
+    left_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("left")))
+    header = find_one(left_panel, Div(cls=Contains("mf-panel-header")))
+    
+    expected = Div(
+      Div("Left"),  # title
+      Div(cls=Contains("mf-panel-hide-icon")),  # hide icon
+      cls="mf-panel-header"
+    )
+    
+    assert matches(header, expected)
+  
+  def test_left_panel_renders_without_title_structure(self, panel_no_title):
+    """Test that left panel without title has legacy structure.
+
+    Why these elements matter:
+    - Order (hide icon, content, resizer): Legacy layout without header
+    - No mf-panel-with-title class
+    """
+    left_panel = find_one(panel_no_title.render(), Div(id=panel_no_title.get_ids().panel("left")))
+    
+    expected = Div(
+      TestIcon("subtract20_regular"),
+      Div(id=panel_no_title.get_ids().left),
+      Div(cls=Contains("mf-resizer-left")),
+      id=panel_no_title.get_ids().panel("left"),
       cls=Contains("mf-panel-left")
     )
     
@@ -274,22 +366,58 @@ class TestPanelRender:
   
   # 3. Right panel
   
-  def test_right_panel_renders_with_correct_structure(self, panel):
+  def test_right_panel_renders_with_title_structure(self, panel):
-    """Test that right panel has resizer before content div.
+    """Test that right panel with title has header + scrollable content.
 
     Why these elements matter:
-    - Order (resizer then hide icon then content): Critical for positioning resizer on the left side
+    - mf-panel-body: Grid container for header + content layout
-    - id: Required for HTMX targeting during toggle/resize operations
+    - mf-panel-header: Contains title and hide icon
-    - cls Contains "mf-panel-right": CSS class for right panel styling
+    - mf-panel-content: Scrollable content area
+    - mf-panel-with-title: Removes default padding-top
     """
     right_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("right")))
     
-    # Step 1: Validate right panel global structure
     expected = Div(
       Div(cls=Contains("mf-resizer-right")),  # resizer
-      TestIcon("subtract20_regular"),  # hide icon
+      Div(cls=Contains("mf-panel-body")),  # body with header + content
-      Div(id=panel.get_ids().right),  # content div, tested in detail later
       id=panel.get_ids().panel("right"),
+      cls=Contains("mf-panel-right", "mf-panel-with-title")
+    )
+    
+    assert matches(right_panel, expected)
+  
+  def test_right_panel_header_contains_title_and_icon(self, panel):
+    """Test that right panel header has title and hide icon.
+
+    Why these elements matter:
+    - Title: Displays the panel title (left aligned)
+    - Hide icon: Allows user to collapse the panel (right aligned)
+    """
+    right_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("right")))
+    header = find_one(right_panel, Div(cls=Contains("mf-panel-header")))
+    
+    expected = Div(
+      Div("Right"),  # title
+      Div(cls=Contains("mf-panel-hide-icon")),  # hide icon
+      cls="mf-panel-header"
+    )
+    
+    assert matches(header, expected)
+  
+  def test_right_panel_renders_without_title_structure(self, panel_no_title):
+    """Test that right panel without title has legacy structure.
+
+    Why these elements matter:
+    - Order (resizer, hide icon, content): Legacy layout without header
+    - No mf-panel-with-title class
+    """
+    right_panel = find_one(panel_no_title.render(), Div(id=panel_no_title.get_ids().panel("right")))
+    
+    expected = Div(
+      Div(cls=Contains("mf-resizer-right")),
+      TestIcon("subtract20_regular"),
+      Div(id=panel_no_title.get_ids().right),
+      id=panel_no_title.get_ids().panel("right"),
       cls=Contains("mf-panel-right")
     )
     
@@ -367,40 +495,57 @@ class TestPanelRender:
   
   # 5. Icons
   
-  def test_hide_icon_in_left_panel_has_correct_command(self, panel):
+  def test_hide_icon_in_left_panel_header(self, panel):
-    """Test that hide icon in left panel triggers toggle_side command.
+    """Test that hide icon in left panel header has correct structure.
 
     Why these elements matter:
     - TestIconNotStr("subtract20_regular"): Verify correct icon is used for hiding
-    - cls Contains "mf-panel-hide-icon": CSS class for hide icon positioning
+    - cls Contains "mf-panel-hide-icon": CSS class for hide icon styling
+    - Icon is inside header when title is shown
     """
     left_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("left")))
+    header = find_one(left_panel, Div(cls=Contains("mf-panel-header")))
     
-    # Find the hide icon (should be wrapped by mk.icon)
+    hide_icons = find(header, Div(cls=Contains("mf-panel-hide-icon")))
-    hide_icons = find(left_panel, Div(cls=Contains("mf-panel-hide-icon")))
+    assert len(hide_icons) == 1, "Header should contain exactly one hide icon"
-    assert len(hide_icons) == 1, "Left panel should contain exactly one hide icon"
     
-    # Verify it contains the subtract icon
     expected = Div(
       TestIconNotStr("subtract20_regular"),
       cls=Contains("mf-panel-hide-icon")
     )
     assert matches(hide_icons[0], expected)
   
-  def test_hide_icon_in_right_panel_has_correct_command(self, panel):
+  def test_hide_icon_in_right_panel_header(self, panel):
-    """Test that hide icon in right panel triggers toggle_side command.
+    """Test that hide icon in right panel header has correct structure.
 
     Why these elements matter:
     - TestIconNotStr("subtract20_regular"): Verify correct icon is used for hiding
-    - cls Contains "mf-panel-hide-icon": CSS class for hide icon positioning
+    - cls Contains "mf-panel-hide-icon": CSS class for hide icon styling
+    - Icon is inside header when title is shown
     """
     right_panel = find_one(panel.render(), Div(id=panel.get_ids().panel("right")))
+    header = find_one(right_panel, Div(cls=Contains("mf-panel-header")))
     
-    # Find the hide icon (should be wrapped by mk.icon)
+    hide_icons = find(header, Div(cls=Contains("mf-panel-hide-icon")))
-    hide_icons = find(right_panel, Div(cls=Contains("mf-panel-hide-icon")))
+    assert len(hide_icons) == 1, "Header should contain exactly one hide icon"
-    assert len(hide_icons) == 1, "Right panel should contain exactly one hide icon"
+    
+    expected = Div(
+      TestIconNotStr("subtract20_regular"),
+      cls=Contains("mf-panel-hide-icon")
+    )
+    assert matches(hide_icons[0], expected)
+  
+  def test_hide_icon_in_panel_without_title(self, panel_no_title):
+    """Test that hide icon is at root level when no title.
+
+    Why these elements matter:
+    - Hide icon should be direct child of panel (legacy behavior)
+    """
+    left_panel = find_one(panel_no_title.render(), Div(id=panel_no_title.get_ids().panel("left")))
+    
+    hide_icons = find(left_panel, Div(cls=Contains("mf-panel-hide-icon")))
+    assert len(hide_icons) == 1, "Panel should contain exactly one hide icon"
     
-    # Verify it contains the subtract icon
     expected = Div(
       TestIconNotStr("subtract20_regular"),
       cls=Contains("mf-panel-hide-icon")
@@ -459,6 +604,26 @@ class TestPanelRender:
     
     assert matches(show_icon, expected)
   
+  @pytest.mark.parametrize("side, conf_kwargs", [
+      ("left", {"show_display_left": False}),
+      ("right", {"show_display_right": False}),
+  ])
+  def test_show_icon_not_in_main_panel_when_show_display_disabled(self, root_instance, side, conf_kwargs):
+    """Test that show icon is not rendered when show_display is disabled.
+
+    Why these elements matter:
+    - Absence of show icon: When show_display_* is False, the icon should not exist
+    - This prevents users from showing the panel via UI (only programmatically)
+    """
+    custom_conf = PanelConf(left=True, right=True, **conf_kwargs)
+    panel = Panel(root_instance, conf=custom_conf)
+    panel.set_main(Div("Main content"))
+    
+    rendered = panel.render()
+    show_icons = find(rendered, Div(id=f"{panel._id}_show_{side}"))
+    
+    assert len(show_icons) == 0, f"Show icon for {side} should not be present when show_display_{side}=False"
+  
   # 6. Main panel
   
   def test_main_panel_contains_show_icons_and_content(self, panel):