function toggleLabels( classname ) {
	var a = [];
	var els = document.getElementsByTagName("span");
	for( var i=0, j=els.length; i<j; i++ ) {
		if( els[i].className == classname ) {
			if (els[i].style.visibility != "") {
				// show label
				els[i].style.visibility = "";
			} else {
				// hide label
				els[i].style.visibility = "hidden";
			}
		}
	}
	updatePHPSession();
}

function updatePHPSession() {
	var xmlHttp;
	try {
		// Firefox, Opera 8.0+, Safari
		xmlHttp = new XMLHttpRequest();
	} catch(e) {
		// Internet Explorer
		try {
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch(e) {
			try {
				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
			} catch(e) {
				alert("Your browser does not support AJAX!");
				return false;
			}
		}
	}
	xmlHttp.onreadystatechange = function() {
		if (xmlHttp.readyState == 4) {
			// empty
		}
	}
	var n = 0;
	var d = 0;
	if (document.getElementById("name").checked) n = 1;
	if (document.getElementById("date").checked) d = 1;
	
	var url = "updatePHPSession.php";
	url = url + "?n=" + n;
	url = url + "&d=" + d;
	url = url + "&sid=" + Math.random();

	xmlHttp.open("GET", url, true);
	xmlHttp.send(null);
}