The source code

    /**
     * @ignore
     *  KISSY Overlay
     * @author yiminghe@gmail.com
     */
    KISSY.add("overlay/overlay-render", function (S, Component, Extension, Loading, Close, Mask) {

        var UA = S.UA;

        return Component.Render.extend([
            Extension.ContentBox.Render,
            Extension.Position.Render,
            Loading,
            UA['ie'] === 6 ? Extension.Shim.Render : null,
            Close,
            Mask
        ]);

    }, {
        requires: [
            "component/base",
            'component/extension',
            './extension/loading-render',
            './extension/close-render',
            './extension/mask-render'
        ]
    });

    /**
     * @ignore
     * 2010-11-09 2010-11-10 yiminghe@gmail.com重构，attribute-base-uibase-Overlay ，采用 UIBase.create
     */