slider.addChangeListener(
      new ChangeListener(){
        public void stateChanged(ChangeEvent e){
          //Restore the background image of the display
          // to all white.
          graphics = display.getGraphics();
          graphics.drawImage(
                          background.getImage(),0,0,null);
                          
          //Rotate the butterfly image, draw it on the
          // display, and repaint the display on the
          // screen..
          rotatePicture(slider.getValue());
          display.repaint();
        }//end stateChanged
      }//end new ChangeListener
    );//end addChangeListener
    //--------------------------------------------------//
  }//end constructor