The source code

    /**
     * @ignore
     * position and visible extension，可定位的隐藏层
     * @author yiminghe@gmail.com
     */
    KISSY.add("component/extension/position-render", function () {

        function Position() {
        }

        Position.ATTRS = {
            x: {
                // 水平方向绝对位置
            },
            y: {
                // 垂直方向绝对位置
            },
            zIndex: {
            },
            /**
             * @ignore
             * see {@link KISSY.Component.Extension.Box#cfg-visibleMode}.
             * Defaults to: "visibility"
             */
            visibleMode: {
                value: "visibility"
            }
        };

        Position.prototype = {

            __createDom: function () {
                this.get("el").addClass(this.get('prefixCls') + "ext-position");
            },

            '_onSetZIndex': function (x) {
                this.get("el").css("z-index", x);
            },

            '_onSetX': function (x) {
                if (x != null) {
                    this.get("el").offset({
                        left: x
                    });
                }
            },

            '_onSetY': function (y) {
                if (y != null) {
                    this.get("el").offset({
                        top: y
                    });
                }
            }
        };

        return Position;
    });