// TODO: typing a number doesn't seem to work?
static <A> JSpinner jListSpinner(L<A> entries, A defaultValue default first(entries)) {
  ret swing(-> {
    new JSpinner s;
    s.setModel(new SpinnerListModel(entries));
    if (contains(entries, defaultValue))
      setSpinnerValue(s, defaultValue);
    ret s;
  });
}