function highlight(id){
		
		var a = document.getElementsByTagName("*");
		
		for (var i = 0; i < a.length; i++) {

			var o = a[i];
			var navblock = /navblock/.exec(o.className);
			
			if(navblock){
				var oid = o.id.split("_");
			
				Element.removeClassName(o.id, "nav_visible");
				Element.addClassName(o.id, "nav_invisible");
								
			}	
		}

		Element.removeClassName("navblock_"+id, "nav_invisible");
		Element.addClassName("navblock_"+id, "nav_visible");
	}