added an event watcher for enter/leave based on signal emission hooks.

added an event watcher for enter/leave based on signal emission hooks.

Mon Nov 30 06:20:36 1998  Tim Janik  <timj@gtk.org>

        * gtk/testgtk.c: added an event watcher for enter/leave based on
        signal emission hooks.

        * gtk/gtkobject.c (gtk_object_class_init): made GtkObject::destroy a
        GTK_RUN_NO_HOOKS signal.

        * gtk/gtksignal.h:
        * gtk/gtksignal.c: implemented emission hooks, new hooks can be added
        to a signal with gtk_signal_add_emission_hook or
        gtk_signal_add_emission_hook_full, and can be removed again with
        gtk_signal_remove_emission_hook.

        * gtk/gtkenums.h: remove GTK_RUN_MASK, since it doesn't represent
        an appropriate mask for signal runtypes for a long time now.
        added GTK_RUN_NO_HOOKS value, which is used to flag signals
        that do not allow the running of signal hooks.