[mutter] window: Set the surface to NULL when unmanaging

[Jasper St. Pierre <jstpierre src gnome org>]

commit 024652bfb45b13a953382cad8840c35ca47c0c5e
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Jul 8 12:13:51 2014 -0400

    window: Set the surface to NULL when unmanaging

 src/core/window.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 36aa9e4..d09e8d6 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -1215,7 +1215,10 @@ meta_window_unmanage (MetaWindow  *window,
   /* This needs to happen for both Wayland and XWayland clients,
    * so it can't be in MetaWindowWayland. */
   if (window->surface)
-    meta_wayland_surface_set_window (window->surface, NULL);
+    {
+      meta_wayland_surface_set_window (window->surface, NULL);
+      window->surface = NULL;
+    }
 
   if (window->visible_to_compositor)
     {