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';
}