var oldtip = null

function showTip(id) {
	var obj = document.getElementById(id);	
	if(obj.style.visibility == "visible") {
		obj.style.visibility = "hidden";
		obj.style.zIndex = "2";
		oldtip = null;
	}
	else {
		if(oldtip != null) {
			oldtip.style.visibility = "hidden";
			oldtip.style.zIndex = "2";
		}
		obj.style.visibility = "visible";
		obj.style.zIndex = "10";
		oldtip = obj;
	}
}

function hideTip(id) {
	var obj = document.getElementById(id);
	obj.style.visibility = "hidden";
	obj.style.zIndex = "2";
	oldtip = null;
}