Sat Mar 14 02:03:13 1998  Tim Janik  <timj@gimp.org>

        * gtk/gtksignal.c: make use of *_by_id() functions for handler key.

        * gtk/gtkwidget.c: make use of *_by_id() functions for a bunch of keys.
        (gtk_widget_shutdown): new function to perform pre-destruction shutdown
        of the widget.
        (gtk_widget_unparent): call gtk_widget_set_parent_window(widget,NULL)

        * gtk/gtkobject.h:
        * gtk/gtkobject.c: GtkObject destruction is now split into an internally
        used shutdown class method and the usual GtkObject::destroy signal
        emission. this allowes for class based shutdown functionality prior
        to actuall object destruction.
        added *_by_id() counterparts for gtk_object_data_* functions, meant for
        internal use only.

        * gtk/gtkmain.c (gtk_quit_add_destroy): new function which will destroy
        a GtkObject once gtk_main() of a certain level finishes. it is save to
        destroy the object prior to that, gtk_quit_add_destroy will only destroy
        objects that are still existing.