function mnu_init() {
	var ul = document.getElementById('topnav');
	var li = ul.firstChild;
	while(li != null) {
		if(li.nodeName == 'LI' && li.lastChild.nodeName == 'UL') {
			li.onmouseover = function() {
				var ul = this.lastChild;
				ul.style.display = "block";
			};
			li.onmouseout = function() {
				var ul = this.lastChild;
				ul.style.display = "none";
			};
		}
		
		li = li.nextSibling;
	}
}

mnu_init();