allego lo script:

codice:
if (document.getElementById){
document.write('<style type="text/css">\n')
document.write('.menu_int{display: none;}\n')
document.write('</style>\n')
}

function SwitchMenu(obj){
	if(document.getElementById){
	var el = document.getElementById(obj);
	var ar = document.getElementById("principale").getElementsByTagName("span");
		if(el.style.display != "block"){
			for (var i=0; i<ar.length; i++){
				if (ar[i].className=="menu_int")
				ar[i].style.display = "none";
			}
			el.style.display = "block";
		}else{
			el.style.display = "none";
		}
	}
}