The source code

    /**
     * @ignore
     *  overlay
     * @author yiminghe@gmail.com
     */
    KISSY.add("overlay", function (S, O, OR, D, DR, P) {
        O.Render = OR;
        D.Render = DR;
        O.Dialog = D;
        S.Dialog = D;
        O.Popup = P;
        S.Overlay = O;
        return O;
    }, {
        requires:[
            "overlay/base",
            "overlay/overlay-render",
            "overlay/dialog",
            "overlay/dialog-render",
            "overlay/popup"
        ]
    });