var Label = {
	center: function(id) {
		var div = document.getElementById('item_label_'+id);
		divLeft = div.offsetLeft;
		divTop = div.offsetTop;
		
		div.style.left = (divLeft - div.offsetWidth/2)+"px";
		div.style.top = (divTop - div.offsetHeight/2)+"px";
	}
}