GTK4: Use eager CASCADE menu population with recursive sendEvent

Co-authored-by: akurtakov <574788+akurtakov@users.noreply.github.com>

Author: Copilot

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Menu.java

@@ -862,33 +862,6 @@ long gtk_show (long widget) {
 	return 0;
 }
 
-@Override
-long notifyProc (long object, long arg0, long user_data) {
-	switch ((int)user_data) {
-		case NOTIFY_VISIBLE:
-			// GTK4: When a BAR or POP_UP menu becomes visible,
-			// fire SWT.Show on all CASCADE sub-menus to enable lazy population
-			if (GTK.GTK4 && (style & SWT.DROP_DOWN) == 0) {
-				// Check if the menu is becoming visible
-				boolean visible = GTK.gtk_widget_get_visible(handle);
-				if (visible) {
-					MenuItem[] items = getItems();
-					for (int i = 0; i < items.length; i++) {
-						MenuItem item = items[i];
-						if ((item.style & SWT.CASCADE) != 0) {
-							Menu subMenu = item.getMenu();
-							if (subMenu != null && !subMenu.isDisposed()) {
-								subMenu.sendEvent(SWT.Show);
-							}
-						}
-					}
-				}
-			}
-			return 0;
-	}
-	return super.notifyProc(object, arg0, user_data);
-}
-
 
 @Override
 long gtk3_show_help (long widget, long helpType) {
@@ -938,9 +911,6 @@ void hookEvents() {
 		if ((style & SWT.DROP_DOWN) == 0) {
 			OS.g_signal_connect_closure_by_id(handle, display.signalIds[SHOW], 0, display.getClosure(SHOW), false);
 			OS.g_signal_connect_closure_by_id(handle, display.signalIds[HIDE], 0, display.getClosure(HIDE), false);
-			
-			// Hook notify::visible to fire SWT.Show on CASCADE sub-menus when parent becomes visible
-			OS.g_signal_connect(handle, OS.notify_visible, display.notifyProc, NOTIFY_VISIBLE);
 		}
 
 	} else {
@@ -1303,6 +1273,25 @@ void setOrientation (boolean create) {
 	}
 }
 
+@Override
+void sendEvent (int eventType) {
+	super.sendEvent(eventType);
+	// GTK4: When sending SWT.Show to a menu, recursively send it to CASCADE sub-menus
+	// This is needed because DROP_DOWN menus don't have widget handles and can't receive signals
+	if (GTK.GTK4 && eventType == SWT.Show) {
+		MenuItem[] items = getItems();
+		for (int i = 0; i < items.length; i++) {
+			MenuItem item = items[i];
+			if ((item.style & SWT.CASCADE) != 0) {
+				Menu subMenu = item.getMenu();
+				if (subMenu != null && !subMenu.isDisposed()) {
+					subMenu.sendEvent(SWT.Show);
+				}
+			}
+		}
+	}
+}
+
 /**
  * Lack of absolute coordinates make Wayland event windows inaccurate.
  * Currently the best approach is to the use the GdkWindow of the mouse

bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/MenuItem.java

@@ -1136,6 +1136,12 @@ public void setMenu (Menu menu) {
 		if (menu != null) {
 			menu.cascade = this;
 			OS.g_menu_item_set_submenu(handle, menu.modelHandle);
+			
+			// GTK4: Manually trigger SWT.Show for DROP_DOWN sub-menu
+			// In GTK4, DROP_DOWN menus don't have widget handles and can't receive signals.
+			// Fire SWT.Show now to populate the menu. The recursive sendEvent override
+			// will also populate nested CASCADE menus.
+			menu.sendEvent(SWT.Show);
 		} else {
 			oldMenu.cascade = null;
 			OS.g_menu_item_set_submenu(handle, 0);