[gtk+/gtk-3-10] x11: Don't crash if a window is on an unmanaged screen

[Benjamin Otte <otte src gnome org>]

commit 6b66716f36ff3323cbb2977b4c213a41e7950f9a
Author: Benjamin Otte <otte redhat com>
Date:   Mon Nov 25 21:11:56 2013 +0100

    x11: Don't crash if a window is on an unmanaged screen
    
    _gdk_x11_display_screen_for_xrootwin() can return NULL. If so, return
    NULL from gdk_x11_window_foreign_new_for_display().
    
    https://bugzilla.gnome.org/show_bug.cgi?id=709716

 gdk/x11/gdkwindow-x11.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 6ee7a96..a8e92b6 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -1229,6 +1229,8 @@ gdk_x11_window_foreign_new_for_display (GdkDisplay *display,
     XFree (children);
 
   screen = _gdk_x11_display_screen_for_xrootwin (display, root);
+  if (screen == NULL)
+    return NULL;
 
   win = _gdk_display_create_window (display);
   win->impl = g_object_new (GDK_TYPE_WINDOW_IMPL_X11, NULL);