The attached patch fixes two vaguely related problems:

 - Glade will save CList column header labels with all sorts 
   of properties, but right now libglade only pays attention 
   to "label", this works fairly well, but annoying warnings
   result:
libglade-WARNING **: Unknown CList child property: visible

 - The sensitive property for toolbar buttons isn't handled:

   https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=85384

libglade-WARNING **: Unknown GtkToolbar child property: sensitive

The attached patch simple suppresses the first warning, and
makes libglade handle the second. It's perhaps not the best
way to handle "sensitive" - since it really should be handled
by g_object_set(), but considering that the toolbar support
will have to be rewritten for the new Toolbar API, probably
good enough.