// f: voidfunc(float)
static JSpinner liveValueSpinner(final LiveValue<Int> lv, int min, int max) {
  final JSpinner spinner = jSpinner(lv!, min, max);
  onChange(spinner, r { lv.setValue(intFromSpinner(spinner)) });
  lv.onChange(r { setSpinnerValue(spinner, lv!) });
  ret spinner;
}