function toggleLayer(whichLayer)
	{
	
		var elem;
		var vis;
		
		if(document.getElementById)
		{

			elem = document.getElementById(whichLayer);
			
		}else if(document.all)
		{
		
			elem = document.all[whichLayer];
			
		}else if(document.layers)
		{
		
			elem = document.layers[whichLayer];
			
		}
		
		vis = elem.style;
		
		if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
		{
		
			vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
			
		}else
		{

			vis.display = (vis.display==''||vis.display=='block')?'none':'block';
			
		}
		
	}