function addLoadListener(func) {
   if (window.addEventListener) {
      window.addEventListener("load", func, false);
   } else if (document.addEventListener) {
      document.addEventListener("load", func, false);
   } else if (window.attachEvent) {
      window.attachEvent("onload", func);
   } else if (typeof window.onload != "function") {
      window.onload = func;
   } else {
      var oldonload = window.onload;
      window.onload = function() {
         oldonload();
         func();
      };
   }
}