The source code

    /**
     * @ignore
     *  controller for overlay
     * @author yiminghe@gmail.com
     */
    KISSY.add("overlay/base", function (S, Component, Extension, Loading, Close, Mask, OverlayRender, OverlayEffect) {

        /**
         * KISSY Overlay Component.
         * xclass: 'overlay'.
         * @class KISSY.Overlay
         * @extends KISSY.Component.Controller
         * @mixins KISSY.Component.Extension.ContentBox
         * @mixins KISSY.Component.Extension.Position
         * @mixins KISSY.Overlay.Extension.Loading
         * @mixins KISSY.Component.Extension.Align
         * @mixins KISSY.Overlay.Extension.Close
         * @mixins KISSY.Overlay.Extension.Mask
         */
        return Component.Controller.extend([
            Extension.ContentBox,
            Extension.Position,
            Loading,
            Extension.Align,
            Close,
            Mask,
            OverlayEffect
        ], {}, {
            ATTRS: {

                /**
                 * overlay can not have focus.
                 *
                 * Defaults to: false.
                 *
                 * @cfg {boolean} focusable
                 * @protected
                 */
                /**
                 * @ignore
                 */
                focusable: {
                    value: false
                },

                /**
                 * overlay can have text selection.
                 *
                 * Defaults to: true.
                 *
                 * @cfg {boolean} allowTextSelection
                 * @protected
                 */
                /**
                 * @ignore
                 */
                allowTextSelection: {
                    value: true
                },

                /**
                 * whether this component can be closed.
                 *
                 * Defaults to: false
                 *
                 * @cfg {Boolean} closable
                 */
                /**
                 * @ignore
                 */
                closable: {
                    value: false
                },

                /**
                 * whether this component can be responsive to mouse.
                 *
                 * Defaults to: false
                 *
                 * @cfg {Boolean} handleMouseEvents
                 * @protected
                 */
                /**
                 * @ignore
                 */
                handleMouseEvents: {
                    value: false
                },
                xrender: {
                    value: OverlayRender
                }
            }
        }, {
            xclass: 'overlay',
            priority: 10
        });
    }, {
        requires: [
            'component/base',
            'component/extension',
            "./extension/loading",
            "./extension/close",
            "./extension/mask",
            './overlay-render',
            './extension/overlay-effect'
        ]
    });