var currentLayer = "1";

function SetVisibleLayer(layer)
{
    var o = null;
    if (o = document.getElementById("layer" + currentLayer))
    {
        o.style.visibility = 'hidden';
    }
    if (o = document.getElementById("layer" + layer))
    {
        o.style.visibility = 'visible';
    }
    if (o = document.getElementById("label" + currentLayer))
    {
        o.style.color = 'black';
    }
    if (o = document.getElementById("label" + layer))
    {
        o.style.color = 'white';
    }

    currentLayer = layer;
}

function SetVisibleLayer_old(layer)
{
	eval("layer" + currentLayer  + ".style.visibility = 'hidden';");
	eval("layer" + layer + ".style.visibility = 'visible'");
	
	eval("label" + currentLayer + ".style.color = 'black'");
	eval("label" + layer + ".style.color = 'white'");

	currentLayer = layer;
}

var queryString = new Array();

function ParseQueryString()
{
	var parameters = window.location.search.substring(1).split('&');
	for (var i=0; i<parameters.length; i++) {
	    var pos = parameters[i].indexOf('=');
	    if (pos > 0) {
	        var paramname = parameters[i].substring(0,pos);
	        var paramval = parameters[i].substring(pos+1);
	        queryString[paramname] = unescape(paramval.replace(/\+/g,' '));
	    } else {
	        queryString[parameters[i]]="" 
	    }
	}
}

ParseQueryString();
if (queryString["tab"]) SetVisibleLayer(queryString["tab"]);
else SetVisibleLayer(1);