static JSlider jliveSlider(int min, int max, int def, final VF1<Float> f) {
  final JSlider slider = new JSlider(min, max, def);
  slider.addChangeListener(new ChangeListener {
    int lastValue = slider.getValue();
    public void stateChanged(ChangeEvent e) {
      int value = slider.getValue();
      if (value != lastValue)
        pcallF(f, lastValue = value;);
    }
  });
  ret slider;
}