var currentLayer;
			var menuTimeout;
	
			function showLayer(id) {			
				document.getElementById(id).style.visibility = "visible";			
			}

			function hideLayer(id) {				
				document.getElementById(id).style.visibility = "hidden";				
			}
			function menuOff(id)
			{
				menuTimeout = setTimeout('hideLayer(currentLayer)',500);
			}
			function menuOn(id)
			{
				if (currentLayer) {
					if (menuTimeout) clearTimeout(menuTimeout);				
					hideLayer(currentLayer);
				}
				showLayer(id);
				currentLayer = id;
			}
			function keepOpen(id)
			{				
				document.getElementById(id).style.visibility = "visible";
				if (menuTimeout) clearTimeout(menuTimeout)
			}