gtkwindow: Use event target widget for WM handling special paths

The check used to achieve discarding events not meant for the window
widget itself (because they are handled in the regular paths). Using
the target widget is the equivalent now.

gtk/gtkwindow.c

@@ -7569,7 +7569,7 @@ static gboolean
 gtk_window_event (GtkWidget *widget,
                   GdkEvent  *event)
 {
-  if (widget != gtk_get_event_widget (event))
+  if (widget != gtk_get_event_target (event))
     return gtk_window_handle_wm_event (GTK_WINDOW (widget), event, FALSE);
 
   return GDK_EVENT_PROPAGATE;