codice:
newBrwSniff=((document.getElementById && !window.opera) || (window.opera && parseInt(navigator.userAgent.substr(navigator.userAgent.lastIndexOf('Opera ')+6))>=7))?1:0;

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

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