[gtk+] gtk_text_buffer_create_tag(): returns NULL on failure

[Sébastien Wilmet <swilmet src gnome org>]

commit 1e3af04dd9a61e2acde4bf86de4f69a24fcb3e22
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Thu Apr 4 13:30:42 2013 +0200

    gtk_text_buffer_create_tag(): returns NULL on failure
    
    Returns NULL in case of a duplicated tag name in the tag table. It is
    still a programmer error to duplicate a name, but if it happens the
    behavior is a little nicer (and hopefully doesn't crash).
    
    https://bugzilla.gnome.org/show_bug.cgi?id=614717

 gtk/gtktextbuffer.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtktextbuffer.c b/gtk/gtktextbuffer.c
index e562c33..6a03b55 100644
--- a/gtk/gtktextbuffer.c
+++ b/gtk/gtktextbuffer.c
@@ -2493,7 +2493,11 @@ gtk_text_buffer_create_tag (GtkTextBuffer *buffer,
 
   tag = gtk_text_tag_new (tag_name);
 
-  gtk_text_tag_table_add (get_table (buffer), tag);
+  if (!gtk_text_tag_table_add (get_table (buffer), tag))
+    {
+      g_object_unref (tag);
+      return NULL;
+    }
 
   if (first_property_name)
     {