ok, this enables the possibility for key-release bindings.

ok, this enables the possibility for key-release bindings.
but nearly no widget really cares to set GDK_KEY_RELEASE_MASK,
which needs to be enabled in order for release bindings to work.

Tue Jun 30 09:24:40 1998  Tim Janik  <timj@gtk.org>

        * gtk/gtkaccelgroup.c (gtk_accelerator_parse): parse "<Release>"
        modifier as well.
        (gtk_accelerator_name): add "<Release>" to the accelerator name if
        neccessary.

        * gtk/gtkbindings.c (BINDING_MOD_MASK): take BINDING_MOD_MASK into
        account.

        * gtk/gtkwidget.c (gtk_widget_real_key_release_event): implemented
        default handler for key-release events, which checks for activation
        of GDK_RELEASE_MASK key bindings.

        * gdk/gdktypes.h (enum): added GDK_RELEASE_MASK to GdkModifierType.