[gtk/applaunch-warning] x11: Ignore stray DestroyNotify events

[Matthias Clasen <matthiasc src gnome org>]

commit 4152e90e7e94d5eccc6feac1ea500d73d9d28db8
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Aug 2 22:43:48 2020 -0400

    x11: Ignore stray DestroyNotify events
    
    There's no use in making a delete event with a
    NULL surface. Just ignore such events.
    
    Fixes: #3006

 gdk/x11/gdkdisplay-x11.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index e895a07867..a2bcefa67d 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -795,7 +795,8 @@ gdk_x11_display_translate_event (GdkEventTranslator *translator,
 
       if (!is_substructure)
        {
-          event = gdk_delete_event_new (surface);
+          if (surface)
+            event = gdk_delete_event_new (surface);
 
          if (surface && GDK_SURFACE_XID (surface) != x11_screen->xroot_window)
            gdk_surface_destroy_notify (surface);