Working on ColumnsManager. Added CycleStateControl and DataGridColumnsManager.

src/myfasthtml/assets/myfasthtml.js

@@ -410,6 +410,18 @@ function getCellId(event) {
   return {cell_id: null};
 }
 
+/**
+ * Check if the click was on a dropdown button element.
+ * Used with hx-vals="js:getDropdownExtra()" for Dropdown toggle behavior.
+ *
+ * @param {MouseEvent} event - The mouse event
+ * @returns {Object} Object with is_button boolean property
+ */
+function getDropdownExtra(event) {
+  const button = event.target.closest('.mf-dropdown-btn');
+  return {is_button: button !== null};
+}
+
 /**
  * Shared utility function for triggering HTMX actions from keyboard/mouse bindings.
  * Handles dynamic hx-vals with "js:functionName()" syntax.
@@ -1498,7 +1510,6 @@ function initDataGridMouseOver(gridId) {
   }
 
   const wrapper = document.getElementById(`tw_${gridId}`);
-  const selectionModeDiv = document.getElementById(`tsm_${gridId}`);
 
   // Track hover state
   let currentHoverRow = null;
@@ -1512,6 +1523,7 @@ function initDataGridMouseOver(gridId) {
     const cell = e.target.closest('.dt2-cell');
     if (!cell) return;
 
+    const selectionModeDiv = document.getElementById(`tsm_${gridId}`);
     const selectionMode = selectionModeDiv?.getAttribute('selection-mode');
 
     if (selectionMode === 'row') {