var N4 = document.layers?true:false;
var DOM2 = document.getElementById?true:false;
var RollerLayer = new Array();
var LastLiv = null;

function Inizia()
   {
   for (i=0 ; i<4 ; i++)
      RollerLayer[i]=N4?document.layers["roller"+i]:DOM2?document.getElementById("roller"+i).style:document.all["roller"+i].style;
   }

function ShowLayer(n)
   {
   RollerLayer[n].visibility="visible";
   LastLiv=n;
   }

function HideLayer(a,b,c)
   {
   RollerLayer[a].visibility = "hidden";
   RollerLayer[b].visibility = "hidden";
   RollerLayer[c].visibility = "hidden";
   }
onload=Inizia;