[Gtk4] Hook dropdown arrow clicked signal in ToolItem

Make sure that coordinates are translated as best as possible so menus
appear in correct places.

Author: akurtakov

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

@@ -308,8 +308,35 @@ void _setVisible (boolean visible) {
 			if (ableToSetLocation()) {
 				if (GTK.GTK4) {
 					GdkRectangle popoverPosition = new GdkRectangle();
-					popoverPosition.x = x;
-					popoverPosition.y = y;
+					/*
+					 * gtk_popover_set_pointing_to expects coordinates in the coordinate
+					 * space of the popover's current parent widget.
+					 *
+					 * When the popover is parented to parent.handle (Shell's GtkFixed),
+					 * setLocation() coordinates need to be translated from the shell
+					 * window's coordinate space (shellHandle / GtkWindow) into the
+					 * GtkFixed's coordinate space. On GTK4 with a header bar, the
+					 * GtkWindow origin is above the client area by the title bar height.
+					 *
+					 * Menus may also be reparented to a control (for example by
+					 * Control.showMenu()), in which case setLocation() can already be
+					 * relative to that control - do not apply the shell to
+					 * parent.handle translation.
+					 */
+					long currentParent = GTK.gtk_widget_get_parent(handle);
+					if (currentParent == parent.handle) {
+						double[] relX = new double[1], relY = new double[1];
+						if (GTK4.gtk_widget_translate_coordinates(parent.getShell().topHandle(), parent.handle, x, y, relX, relY)) {
+							popoverPosition.x = (int) relX[0];
+							popoverPosition.y = (int) relY[0];
+						} else {
+							popoverPosition.x = x;
+							popoverPosition.y = y;
+						}
+					} else {
+						popoverPosition.x = x;
+						popoverPosition.y = y;
+					}
 					popoverPosition.width = popoverPosition.height = 1;
 					GTK.gtk_popover_set_pointing_to(handle, popoverPosition);
 

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

@@ -868,6 +868,42 @@ long gtk_mnemonic_activate (long widget, long arg1) {
 	return parent.gtk_mnemonic_activate (widget, arg1);
 }
 
+@Override
+int gtk_gesture_press_event(long gesture, int n_press, double x, double y, long event) {
+	/*
+	 * GTK4: For DROP_DOWN items, the arrow portion is a GtkMenuButton
+	 * (arrowHandle) that is separate from the main button. Attach a gesture
+	 * controller to arrowHandle and detect it here in order to send the
+	 * SWT.ARROW selection detail to the listener (e.g. to open a drop-down menu).
+	 */
+	if ((style & SWT.DROP_DOWN) != 0 && arrowHandle != 0
+			&& GTK.gtk_event_controller_get_widget(gesture) == arrowHandle
+			&& n_press == 1
+			&& GTK.gtk_gesture_single_get_current_button(gesture) == 1) {
+		Event e = new Event();
+		e.detail = SWT.ARROW;
+		GtkAllocation allocation = new GtkAllocation();
+		GTK.gtk_widget_get_allocation(arrowHandle, allocation);
+		/*
+		 * On GTK4 gtk_widget_get_allocation returns parent-widget-relative
+		 * coordinates, but the SWT event x/y must be in ToolBar-relative
+		 * coordinates so that callers can use toolBar.toDisplay(event.x, event.y).
+		 * Translate the arrow button's origin into the ToolBar's coordinate space.
+		 * If translation fails, fall back to the parent-relative allocation.
+		 */
+		double[] destX = new double[1];
+		double[] destY = new double[1];
+		boolean translated = GTK4.gtk_widget_translate_coordinates(arrowHandle, parent.handle, 0, 0, destX, destY);
+		e.x = translated ? (int) destX[0] : allocation.x;
+		if ((parent.style & SWT.MIRRORED) != 0) e.x = parent.getClientWidth() - allocation.width - e.x;
+		System.out.println(e.x);
+		e.y = translated ? (int) destY[0] + allocation.height : allocation.y + allocation.height;
+		sendSelectionEvent(SWT.Selection, e, false);
+		return GTK4.GTK_EVENT_SEQUENCE_CLAIMED;
+	}
+	return GTK4.GTK_EVENT_SEQUENCE_NONE;
+}
+
 @Override
 void hookEvents () {
 	super.hookEvents ();
@@ -1664,4 +1700,4 @@ private void recreateMenuProxy() {
 		}
 	}
 }
-}
+}