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