/*
        * Links the JButtons and the graphic sequences to display the lights
        * 
        */
       if(event.getSource() == GO) //display green if GO is clicked 
       {
           clickGO = true;
           carX -=15; 
           repaint();
           }
           if (event.getSource() == WAIT) //display yellow if WAIT is clicked
           {
               clickWAIT = true;
               repaint();
               }
               if (event.getSource() == STOP) //display red if STOP is clicked
               {
                   clickSTOP = true;
                   repaint();
                   }