function toggleLayer(whichLayer)
{
	var elem;
	var 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(vis.display == '' && elem.offsetWidth != null && elem.offsetHeight != null)
	{
		vis.display = (elem.offsetWidth != 0 && elem.offsetHeight != 0) ? 'block' : 'none';
	}
	
	vis.display = (vis.display == '' || vis.display == 'block') ? 'none' : 'block';
}