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

if (document.all && document.getElementById && document.createTextNode && window.attachEvent) {
	addLoadEvent(function() {
		var nodes = document.getElementById("dropdown").getElementsByTagName("LI");
		for (var i=0; i<nodes.length; i++) {
			nodes[i].onmouseover = function() {
				this.className += " menu-over";
			}
			nodes[i].onmouseout = function() {
				this.className = this.className.replace(new RegExp(" menu-over\\b"), "");
			}
		}
	});
}