strictly check for the associated get/set arg functions. if an arg is

strictly check for the associated get/set arg functions. if an arg is

Fri Jul 10 13:29:53 1998  Tim Janik  <timj@gtk.org>

        * gtk/gtkcontainer.c:
        (gtk_container_arg_get):
        (gtk_container_arg_set):
        * gtk/gtkobject.c:
        (gtk_object_arg_set):
        (gtk_object_arg_get):
        strictly check for the associated get/set arg functions. if an
        arg is readable or writable, the associated class functions *must*
        be provided.