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';
}