sclass CircleDoubleClicker extends MouseAdapter {
  CirclesAndLines cal;
  Canvas canvas;
  O onClick;

  *(CirclesAndLines *cal, Canvas canvas) {
    if (containsInstance(is.tools, CircleDoubleClicker)) ret;
    is.tools.add(this);
    is.addMouseListener(this);
  }

  public void mouseClicked(MouseEvent e) {
    if (e.getButton() == MouseEvent.BUTTON1 && e.getClickCount() == 2) {
      Pt p = is.pointFromEvent(e);
      circle = cal.findCircle(p);
      if (circle != null)
        pcallF(onClick, circle);
    }
  }
}