Listing 6

handle_event on_rclick() {
  // on right-click, shows a context menu (first sub-menu)
  menu<owned> m(menu_::group::sample_start);
  m.sub_menu(0).run_popup( cursor_pos(), window());
  return event_ex<wm::left_button_down>().HANDLED_BY(&me::on_rclick);
}