[gtk+] Avoid a critical under weston

[Matthias Clasen <matthiasc src gnome org>]

commit 62b858cf0f74b44133a77d0e99c497cabc1a2ab0
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 11 22:13:07 2015 -0400

    Avoid a critical under weston
    
    The ordering of globals in connection setup under weston
    is different from mutter, and we end up creating a the
    dnd window before any outputs are present. Don't cause
    a critical warning in that case.

 gdk/wayland/gdkwindow-wayland.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gdk/wayland/gdkwindow-wayland.c b/gdk/wayland/gdkwindow-wayland.c
index a4e1df4..507013c 100644
--- a/gdk/wayland/gdkwindow-wayland.c
+++ b/gdk/wayland/gdkwindow-wayland.c
@@ -495,7 +495,8 @@ _gdk_wayland_display_create_window_impl (GdkDisplay    *display,
   g_object_ref (window);
 
   /* More likely to be right than just assuming 1 */
-  if (wayland_display->compositor_version >= WL_SURFACE_HAS_BUFFER_SCALE)
+  if (wayland_display->compositor_version >= WL_SURFACE_HAS_BUFFER_SCALE &&
+      gdk_screen_get_n_monitors (screen) > 0)
     impl->scale = gdk_screen_get_monitor_scale_factor (screen, 0);
 
   impl->title = NULL;