/*
Global "swap" holder
Use value, null, if no layer initially visible
*/
var currLayerId = null;

function togLayer(id)
{
if(currLayerId) setDisplay(currLayerId, "none");
if(id)setDisplay(id, "block");
currLayerId = id;
}

function setDisplay(id,value)
{
var elm = document.getElementById(id);
elm.style.display = value;
}