sclass MouseInComponentMonitor extends BoolVarWithNotify is MouseListener, MouseMotionListener {
  JComponent component;
  
  *() {}
  *(JComponent component) { init(component); }
  
  void init(JComponent component) {
    if (this.component != null) fail("Already initialized");
    this.component = component;
    addMouseMotionListener(component, this);
  }
  
  public void mouseEntered(MouseEvent e) { set(true); }
  public void mouseExited(MouseEvent e) { set(false); }
  public void mouseMoved(MouseEvent e) { set(true); }
  public void mouseDragged(MouseEvent e) { /*set(true);*/ }
}