I'd like to propose

        * gtk-1.2.defs (gtk_main_iteration, gtk_main_iteration_do, gtk_true,
        gtk_false, gtk_events_pending): Make returns #t/#f.

Currently these return integers to scheme, but I think they're all
just TRUE or FALSE at the C level and might be better as #t/#f.

In gtk 1.2 the C return types are gint, but in 2.2 this seems to have
been corrected to gboolean.

Hopefully no-one has used gtk-events-pending thinking it was a count
of pending events or something, which it's not.