[gtk+] gtkmenubutton: set menu to NULL in dispose.

[Paolo Borelli <pborelli src gnome org>]

commit 583036378706ab03822f30ce311c41293d482d6c
Author: Paolo Borelli <pborelli gnome org>
Date:   Sun Nov 4 12:09:23 2012 +0100

    gtkmenubutton: set menu to NULL in dispose.
    
    Prevent menu to be detached multiple times.

 gtk/gtkmenubutton.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmenubutton.c b/gtk/gtkmenubutton.c
index 09ec60d..5416d37 100644
--- a/gtk/gtkmenubutton.c
+++ b/gtk/gtkmenubutton.c
@@ -911,6 +911,7 @@ gtk_menu_button_dispose (GObject *object)
                                             menu_deactivate_cb,
                                             object);
       gtk_menu_detach (GTK_MENU (priv->popup));
+      priv->popup = NULL;
     }
 
   g_clear_object (&priv->model);