The source code

    /**
     * @ignore
     *  Single tab in tab bar.
     * @author yiminghe@gmail.com
     */
    KISSY.add("tabs/tab", function (S, Button, TabRender) {

        /**
         * KISSY.Tabs.Tab
         * @class KISSY.Tabs.Tab
         * @extends KISSY.Button
         */
        return Button.extend({
            isTabsTab: true,
            bindUI: function () {
                this.on("click", function () {
                    this.set("selected", true);
                });
            }
        }, {
            ATTRS: {
                handleMouseEvents: {
                    value: false
                },
                focusable: {
                    value: false
                },
                /**
                 * whether selected
                 * @cfg {Boolean} selected
                 */
                /**
                 * @ignore
                 */
                selected: {
                    view: 1
                },
                selectedCls: {
                    view: 1
                },
                xrender: {
                    value: TabRender
                }
            }
        }, {
            xclass: 'tabs-tab',
            priority: 30
        });

    }, {
        requires: ['button', './tab-render']
    });