function initMenuRollover() {
	var cnt=document.getElementById("animazione");
	var cnt_imgs=cnt.getElementsByTagName("img");
	for(var i=0;i<cnt_imgs.length;i++) {
		cnt_imgs[i].onmouseover=function() {
			this.src=(this.src).replace("_off.jpg","_on.jpg");
		}
		cnt_imgs[i].onmouseout=function() {
			this.src=(this.src).replace("_on.jpg","_off.jpg");
		}
	}
}

addLoadEvent(initMenuRollover);