I believe that the callback given to g_object_set_qdata_full() should be called when the GObject is destroyed, but it doesn't seem to work in this simple test case: http://bugzilla.gnome.org/showattachment.cgi?attach_id=17788 Have I made a simple mistake in that test code, or am I misunderstanding something? We use this in the internals of gtkmm and I'm sure it works most of the time, so I am confused. We can of course just connect to the "destroy" signal if we can't get this to work consistently. Murray Cumming murrayc@usa.net www.murrayc.com