    /**
     * Component layout for tabs
     * @private
     */
    Ext.define('Ext.layout.component.Tab', {

        extend: 'Ext.layout.component.Button',
        alias: 'layout.tab',

        beginLayout: function(ownerContext) {
            var me = this,
                closable = me.owner.closable;

            // Changing the close button visibility causes our cached measurements to be wrong,
            // so we must convince our base class to re-cache those adjustments...
            if (me.lastClosable !== closable) {
                me.lastClosable = closable;
                me.clearTargetCache();
            }

            me.callParent(arguments);
        }
    });