var ul = document.getElementById("mainlevelnav").getElementsByTagName("ul");
for(var i=0, l=ul.length; i<l; i++) {
	var li = ul[i].parentNode;
	li.ls = ul[i].style;
	li.onmouseover = showup;
	li.onmouseout = disappear;
}	

function showup() {
	if (this.up) clearTimeout(this.up);
	this.ls.visibility = 'visible';					  

}			

function disappear() {
	var me = this;
	this.up = setTimeout(function(){ me.ls.visibility = 'hidden';}, 400);	
}