I tried to run examples/tictactoe.scm and noticed gtk-class-new and
gtk-signal-new-generic seem to have bit-rotted slightly.

        * guile-gtk.c (gtk_class_new): Use gtk_type_query rather than
        gtk_type_get_info.
        (gtk_signal_new_generic): Use sgtk_callback_marshal for marshalling.

Not sure if this is actually right, but it takes it from not working
to seeming to work. :)

I see the gtk changelog says gtk_type_get_info got reverted.  I guess
gtk_type_query is the way to go, for gtk 1.2 at least.  Unless anyone
knows better I'd think it could be used unconditionally, no need for
an autoconf check by now.