// runnable must implement a "run(S)" method
static JFrame swingChoose(L<S> options, fO runnable) {
  final JFrame[] frame = new JFrame[1];
  new L parts;
  for (final S s : options)
    parts.add(newButton(s, runnable {
      frame[0].dispose();
      callOpt(runnable, "run", s);
    }));
  ret frame[0] = showPackedFrame("Please choose", vgrid(parts));
}

Began life as a copy of #1003293