public void mouseClicked(MouseEvent e) {
   log.info("" + hot.idx);
   if (e.getButton() == MouseEvent.BUTTON1) {
     int mask = 1 << hot.idx;
     if (e.isShiftDown()) {
       int old = panel.getSelectedMask();
       if ((mask & old) == 0) mask |= old;
       else mask = ~mask & old;
     }
     panel.setSelectedMask(mask);
   }
 }