[gtk+] Make gdk_display_open_default_libgtk_only more robust

[Matthias Clasen <matthiasc src gnome org>]

commit 48d8af85d08b8937f4105535d88302c7a20909aa
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Mar 23 19:40:16 2013 -0400

    Make gdk_display_open_default_libgtk_only more robust
    
    Make this function return NULL if GDK could not be
    initialized. We check this by seeing if there is a
    display manager singleton.

 gdk/gdk.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gdk/gdk.c b/gdk/gdk.c
index 5d0dc1c..31fe065 100644
--- a/gdk/gdk.c
+++ b/gdk/gdk.c
@@ -350,7 +350,7 @@ gdk_get_display_arg_name (void)
  *
  * Opens the default display specified by command line arguments or
  * environment variables, sets it as the default display, and returns
- * it.  gdk_parse_args must have been called first. If the default
+ * it. gdk_parse_args() must have been called first. If the default
  * display has previously been set, simply returns that. An internal
  * function that should not be used by applications.
  *
@@ -364,6 +364,9 @@ gdk_display_open_default_libgtk_only (void)
 
   g_return_val_if_fail (gdk_initialized, NULL);
 
+  if (gdk_display_manager_peek () == NULL)
+    return NULL;
+
   display = gdk_display_get_default ();
   if (display)
     return display;