Listing 6

(a)
handle_event on_tri(wm::tri_click::arg a) {
  ...
  return event_ex<wm::tri_click>().HANDLED_BY(&me::on_tri);
}


(b)
// assuming it comes from m_ok button
handle_event on_tri(m_ok_::ev::tri_click::arg a) {
  ...
  return event_ex<m_ok_::ev::tri_click>().HANDLED_BY(&me::on_tri);
}