function toggleLayer( whichLayer )
{
	for (i=0; i<document.getElementById("contenttable").childNodes.length; i++){
		if (document.getElementById("contenttable").childNodes[i].nodeName=="DIV") {
			if (whichLayer == 'all') {
				document.getElementById("contenttable").childNodes[i].style.display = 'block';
			} else {
				document.getElementById("contenttable").childNodes[i].style.display = 'none';
			}
		}
	}
	document.getElementById(whichLayer).style.display = 'block';

//	document.getElementById(whichLayer).style.display = 'none';
}