function toggleLayer( whichLayer ){
		var elem, 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';
		vis.display = (vis.display==''||vis.display=='block')?'none':'block';
}