@Override
 public void mouseExited(MouseEvent e) {
   super.mouseExited(e);
 }
 public void register(Chart chart) {
   super.register(chart);
   chart.getCanvas().addMouseController(this);
 }
 public void dispose() {
   for (Chart chart : targets) {
     chart.getCanvas().removeMouseController(this);
   }
   super.dispose();
 }
 @Override
 public void mouseReleased(MouseEvent e) {
   super.mouseReleased(e);
 }