var left = helper.parent[0].offsetLeft;
		var top = helper.parent[0].offsetTop;
		if(event) {
			// position the helper 15 pixel to bottom right, starting from mouse position
			left = event.pageX + 15;
			top = event.pageY + 15;
			helper.parent.css({
				left: left + 'px',
				top: top + 'px'
			});
		}