function toggleLayer( whichLayer )
	{
		var elem, vis;
		if( document.getElementById ) // this is the way the standards work
	    	elem = document.getElementById( whichLayer );
		else if( document.all ) // this is the way old msie versions work
			elem = document.all[whichLayer];
		else if( document.layers ) // this is the way nn4 works
			elem = document.layers[whichLayer];
			vis = elem.style;
		// if the style.display value is blank we try to figure it out here
		if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
			vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
			vis.display = (vis.display==''||vis.display=='block')?'none':'block';
	}