[gtk+] x11: Fix compiler warning

[Benjamin Otte <otte src gnome org>]

commit 6318e5e5d147008bd3a09b63214e5e4226a891fc
Author: Benjamin Otte <otte redhat com>
Date:   Tue Aug 27 15:59:38 2013 +0200

    x11: Fix compiler warning

 gdk/x11/gdkwindow-x11.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 4dc632f..cff720e 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -2159,7 +2159,7 @@ get_netwm_cardinal_property (GdkWindow   *window,
 guint32
 gdk_x11_window_get_desktop (GdkWindow *window)
 {
-  g_return_if_fail (GDK_IS_WINDOW (window));
+  g_return_val_if_fail (GDK_IS_WINDOW (window), 0);
 
   return get_netwm_cardinal_property (window, "_NET_WM_DESKTOP");
 }