gesture: Protect against odd window hierarchies

If no match is found with the gesture widget when poking the event
window parents, bail out safely instead of falling in an infinite
loop. This was seen on Mutter.

diff --git a/gtk/gtkgesture.c b/gtk/gtkgesture.c
index e1f03d8dd92f5605df267b0ff654698ac5aec89f..30d944a76ce64533e379fe682446a0aea674c258 100644 (file)
--- a/gtk/gtkgesture.c
+++ b/gtk/gtkgesture.c
@@ -318,7 +318,7 @@ _update_widget_coordinates (GtkGesture *gesture,
   gdk_event_get_coords (data->event, &event_x, &event_y);
   window = data->event->any.window;
 
-  while (window != event_widget_window)
+  while (window && window != event_widget_window)
     {
       gdk_window_get_position (window, &wx, &wy);
       event_x += wx;
@@ -326,6 +326,9 @@ _update_widget_coordinates (GtkGesture *gesture,
       window = gdk_window_get_effective_parent (window);
     }
 
+  if (!window)
+    return;
+
   if (!gtk_widget_get_has_window (event_widget))
     {
       gtk_widget_get_allocation (event_widget, &allocation);