function addLoadEvent(func) { 
      var oldonload = window.onload; 
      if (typeof window.onload != 'function') { 
        window.onload = func; 
      } else { 
        window.onload = function() { 
          if (oldonload) { 
            oldonload(); 
          } 
          func(); 
        } 
      } 
    } 
addLoadEvent(display1);