    /**
     * @author Ed Spencer
     * @class Ext.tab.Tab
     * @extends Ext.button.Button
     *
     * <p>Represents a single Tab in a {@link Ext.tab.Panel TabPanel}. A Tab is simply a slightly customized {@link Ext.button.Button Button},
     * styled to look like a tab. Tabs are optionally closable, and can also be disabled. 99% of the time you will not
     * need to create Tabs manually as the framework does so automatically when you use a {@link Ext.tab.Panel TabPanel}</p>
     */
    Ext.define('Ext.tab.Tab', {
        extend: 'Ext.button.Button',
        alias: 'widget.tab',

        requires: [
            'Ext.layout.component.Tab',
            'Ext.util.KeyNav'
        ],

        componentLayout: 'tab',

        isTab: true,

        baseCls: Ext.baseCSSPrefix + 'tab',

        /**
         * @cfg {String} activeCls
         * The CSS class to be applied to a Tab when it is active. Defaults to 'x-tab-active'.
         * Providing your own CSS for this class enables you to customize the active state.
         */
        activeCls: 'active',

        /**
         * @cfg {String} disabledCls
         * The CSS class to be applied to a Tab when it is disabled. Defaults to 'x-tab-disabled'.
         */

        /**
         * @cfg {String} closableCls
         * The CSS class which is added to the tab when it is closable
         */
        closableCls: 'closable',

        /**
         * @cfg {Boolean} closable True to make the Tab start closable (the close icon will be visible). Defaults to true
         */
        closable: true,

        /**
         * @cfg {String} closeText
         * The accessible text label for the close button link; only used when {@link #closable} = true.
         * Defaults to 'Close Tab'.
         */
        closeText: 'Close Tab',

        /**
         * @property Boolean
         * Read-only property indicating that this tab is currently active. This is NOT a public configuration.
         */
        active: false,

        /**
         * @property closable
         * @type Boolean
         * True if the tab is currently closable
         */

        scale: false,

        position: 'top',

        initComponent: function() {
            var me = this;

            me.addEvents(
                /**
                 * @event activate
                 * @param {Ext.tab.Tab} this
                 */
                'activate',

                /**
                 * @event deactivate
                 * @param {Ext.tab.Tab} this
                 */
                'deactivate',

                /**
                 * @event beforeclose
                 * Fires if the user clicks on the Tab's close button, but before the {@link #close} event is fired. Return
                 * false from any listener to stop the close event being fired
                 * @param {Ext.tab.Tab} tab The Tab object
                 */
                'beforeclose',

                /**
                 * @event beforeclose
                 * Fires to indicate that the tab is to be closed, usually because the user has clicked the close button.
                 * @param {Ext.tab.Tab} tab The Tab object
                 */
                'close'
            );

            me.callParent(arguments);

            if (me.card) {
                me.setCard(me.card);
            }
        },

        /**
         * @ignore
         */
        onRender: function() {
            var me = this;

            me.addClsWithUI(me.position);

            // Set all the state classNames, as they need to include the UI
            // me.disabledCls = me.getClsWithUIs('disabled');

            me.syncClosableUI();

            me.callParent(arguments);

            if (me.active) {
                me.activate(true);
            }

            me.syncClosableElements();

            me.keyNav = Ext.create('Ext.util.KeyNav', me.el, {
                enter: me.onEnterKey,
                del: me.onDeleteKey,
                scope: me
            });
        },

        // inherit docs
        enable : function(silent) {
            var me = this;

            me.callParent(arguments);

            me.removeClsWithUI(me.position + '-disabled');

            return me;
        },

        // inherit docs
        disable : function(silent) {
            var me = this;

            me.callParent(arguments);

            me.addClsWithUI(me.position + '-disabled');

            return me;
        },

        /**
         * @ignore
         */
        onDestroy: function() {
            var me = this;

            if (me.closeEl) {
                me.closeEl.un('click', Ext.EventManager.preventDefault);
                me.closeEl = null;
            }

            Ext.destroy(me.keyNav);
            delete me.keyNav;

            me.callParent(arguments);
        },

        /**
         * Sets the tab as either closable or not
         * @param {Boolean} closable Pass false to make the tab not closable. Otherwise the tab will be made closable (eg a
         * close button will appear on the tab)
         */
        setClosable: function(closable) {
            var me = this;

            // Closable must be true if no args
            closable = (!arguments.length || !!closable);

            if (me.closable != closable) {
                me.closable = closable;

                // set property on the user-facing item ('card'):
                if (me.card) {
                    me.card.closable = closable;
                }

                me.syncClosableUI();

                if (me.rendered) {
                    me.syncClosableElements();

                    // Tab will change width to accommodate close icon
                    me.doComponentLayout();
                    if (me.ownerCt) {
                        me.ownerCt.doLayout();
                    }
                }
            }
        },

        /**
         * This method ensures that the closeBtn element exists or not based on 'closable'.
         * @private
         */
        syncClosableElements: function () {
            var me = this;

            if (me.closable) {
                if (!me.closeEl) {
                    me.closeEl = me.el.createChild({
                        tag: 'a',
                        cls: me.baseCls + '-close-btn',
                        href: '#',
                        // html: me.closeText, // removed for EXTJSIV-1719, by rob@sencha.com
                        title: me.closeText
                    }).on('click', Ext.EventManager.preventDefault);  // mon ???
                }
            } else {
                var closeEl = me.closeEl;
                if (closeEl) {
                    closeEl.un('click', Ext.EventManager.preventDefault);
                    closeEl.remove();
                    me.closeEl = null;
                }
            }
        },

        /**
         * This method ensures that the UI classes are added or removed based on 'closable'.
         * @private
         */
        syncClosableUI: function () {
            var me = this, classes = [me.closableCls, me.closableCls + '-' + me.position];

            if (me.closable) {
                me.addClsWithUI(classes);
            } else {
                me.removeClsWithUI(classes);
            }
        },

        /**
         * Sets this tab's attached card. Usually this is handled automatically by the {@link Ext.tab.Panel} that this Tab
         * belongs to and would not need to be done by the developer
         * @param {Ext.Component} card The card to set
         */
        setCard: function(card) {
            var me = this;

            me.card = card;
            me.setText(me.title || card.title);
            me.setIconCls(me.iconCls || card.iconCls);
        },

        /**
         * @private
         * Listener attached to click events on the Tab's close button
         */
        onCloseClick: function() {
            var me = this;

            if (me.fireEvent('beforeclose', me) !== false) {
                if (me.tabBar) {
                    if (me.tabBar.closeTab(me) === false) {
                        // beforeclose on the panel vetoed the event, stop here
                        return;
                    }
                } else {
                    // if there's no tabbar, fire the close event
                    me.fireEvent('close', me);
                }
            }
        },

        /**
         * Fires the close event on the tab.
         * @private
         */
        fireClose: function(){
            this.fireEvent('close', this);
        },

        /**
         * @private
         */
        onEnterKey: function(e) {
            var me = this;

            if (me.tabBar) {
                me.tabBar.onClick(e, me.el);
            }
        },

       /**
         * @private
         */
        onDeleteKey: function(e) {
            var me = this;

            if (me.closable) {
                me.onCloseClick();
            }
        },

        // @private
        activate : function(supressEvent) {
            var me = this;

            me.active = true;
            me.addClsWithUI([me.activeCls, me.position + '-' + me.activeCls]);

            if (supressEvent !== true) {
                me.fireEvent('activate', me);
            }
        },

        // @private
        deactivate : function(supressEvent) {
            var me = this;

            me.active = false;
            me.removeClsWithUI([me.activeCls, me.position + '-' + me.activeCls]);

            if (supressEvent !== true) {
                me.fireEvent('deactivate', me);
            }
        }
    });