[gtk+] GtkBox: Fix self-assignment for center widget

[Matthias Clasen <matthiasc src gnome org>]

commit 8b6457732f2c7723b2415bf3dddc734219eeca2e
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Oct 25 20:27:18 2014 -0400

    GtkBox: Fix self-assignment for center widget
    
    This is happening when glade is loading ui files containing
    center widgets.

 gtk/gtkbox.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkbox.c b/gtk/gtkbox.c
index 72f26e9..2fb1c0d 100644
--- a/gtk/gtkbox.c
+++ b/gtk/gtkbox.c
@@ -2616,17 +2616,22 @@ gtk_box_set_center_widget (GtkBox    *box,
                            GtkWidget *widget)
 {
   GtkBoxPrivate *priv = box->priv;
+  GtkWidget *old_center = NULL;
 
   g_return_if_fail (GTK_IS_BOX (box));
 
   if (priv->center)
     {
+      old_center = g_object_ref (priv->center->widget);
       gtk_box_remove (GTK_CONTAINER (box), priv->center->widget);
       priv->center = NULL;
     }
 
   if (widget)
     priv->center = gtk_box_pack (box, widget, FALSE, TRUE, 0, GTK_PACK_START);
+
+  if (old_center)
+    g_object_unref (old_center);
 }
 
 /**