function preload(){
	var menu_items = document.getElementsByName("menu_item");
	for(var i=0; i!=menu_items.length; ++i){
		menu_items[i].onmouseover=function(){this.style.backgroundColor="rgb(255,255,255)";};
		menu_items[i].onmouseout=function(){this.style.backgroundColor="rgb(220,220,220)";};
	}
}