[gtk+] Improve warning

[Matthias Clasen <matthiasc src gnome org>]

commit bb41cfe9d945082ea1db704684c40d78edf46eb0
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Oct 30 13:41:13 2014 -0400

    Improve warning
    
    Mention the file that we're failing to load. That makes it obvious
    what is wrong.

 demos/widget-factory/widget-factory.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/demos/widget-factory/widget-factory.c b/demos/widget-factory/widget-factory.c
index a9a36e6..d6bdf93 100644
--- a/demos/widget-factory/widget-factory.c
+++ b/demos/widget-factory/widget-factory.c
@@ -761,7 +761,7 @@ background_loaded_cb (GObject      *source,
   pixbuf = gdk_pixbuf_new_from_stream_finish (res, &error);
   if (error)
     {
-      g_warning ("%s", error->message);
+      g_warning ("Error loading '%s': %s", bd->filename, error->message);
       g_error_free (error);
       return;
     }