var navActived = null;

function bindNavEvent() {
	var navigator = document.getElementById('navigator').childNodes[0];
	for (i=0; i<navigator.childNodes.length; i++) {
		node = navigator.childNodes[i];
		if (node.nodeName=="LI") {
			node.onmouseover=function() {
				if(navActived) {
					navActived.className=this.className.replace(" over", "");
				}

				this.className+=" over";
				navActived = this;
			}
		}
	}
}

addEvent(window, 'load', bindNavEvent);