[mutter] bell: Fallback to fullscreen flash if no window was passed

[Jonas Ådahl <jadahl src gnome org>]

commit 92c8a51ba68b29c7209acf03ae3e33099d973e5f
Author: Jonas Ådahl <jadahl gmail com>
Date:   Sat Mar 19 11:28:42 2016 +0800

    bell: Fallback to fullscreen flash if no window was passed
    
    We allow to flash without providing a window. In this case we should
    flash the whole screen, instead of crashing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=763858

 src/core/bell.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/core/bell.c b/src/core/bell.c
index 1afbf0a..56967bb 100644
--- a/src/core/bell.c
+++ b/src/core/bell.c
@@ -152,8 +152,10 @@ bell_flash_frame (MetaDisplay *display,
 {
   if (window && window->frame)
     bell_flash_window_frame (window);
-  else
+  else if (window)
     bell_flash_window (window);
+  else
+    bell_flash_fullscreen (display);
 }
 
 /**