yii\bootstrap\Tabs::run PHP Method

    public function run()
    {
        $this->registerPlugin('tab');
        return $this->renderItems();
    }

 public function run()
 {
     TabsAsset::register($this->getView());
     if (!$this->hasActiveTab() && !empty($this->items)) {
         reset($this->items);
         $this->items[key($this->items)]['active'] = true;
     }
     return parent::run();
 }