var NS4 = (document.layers) ? 1 : 0;
var IE4 = (document.all) ? 1 : 0;
var W3C= (document.getElementById) ? 1 : 0;
var DYN=(NS4 || IE4 || W3C);

var i = 1;
var flag = "layer";

if (DYN)
{
	function activateLayer(layer_no)
	{
	    hiding(eval('"' + flag + i +'"'));
	    showing(eval('"' + flag + layer_no +'"')); 
	    i = layer_no; 
	    return true;
	}

	function hidealllayers(e)
	{
		var n=1;

		while(exists(n))
		{
			hiding(eval('"' + flag + n + '"'));
			n++;
		}
	}
}

function exists(nr)
{
	if (NS4) { return document.layers.length>=nr; }
	else if (IE4){ return document.all[flag+nr]!=null;  }
	   else if(W3C) { return document.getElementById(flag+nr)!=null;}
}
	
function showing(id)
{   
	if (NS4) {document.layers[id].visibility = "show"; }
	else if (IE4){document.all[id].style.visibility = "visible";  }
	   else if(W3C) {document.getElementById(id).style.visibility="visible";}
}

function hiding(id)
{
	if (NS4){document.layers[id].visibility = "hide"; }
	else if (IE4){document.all[id].style.visibility = "hidden";  }
	   else if (W3C) {document.getElementById(id).style.visibility="hidden";}
}

//reloads the window if Nav4 resized				  
function reloadPage(init)
{  
	if (init==true) with (navigator) {if (NS4) {
	document.pgW=innerWidth; document.pgH=innerHeight; onresize=reloadPage; }}
	else if (innerWidth!=document.pgW || innerHeight!=document.pgH) location.reload();
}

reloadPage(true);

document.onmouseup=hidealllayers;
if(NS4) window.captureEvents(Event.MOUSEUP);
window.onmouseup=hidealllayers;