/**
  * Renders the widget.
  */
 public function run()
 {
     $this->registerPlugin('button');
     if ($this->includeContainer) {
         Html::addCssClass($this->containerOptions, 'btn-group');
         $options = $this->containerOptions;
         $tag = ArrayHelper::remove($options, 'tag', 'div');
         return implode("\n", [Html::beginTag($tag, $options), $this->renderButton(), $this->renderDropdown(), Html::endTag($tag)]);
     } else {
         return implode("\n", [$this->renderButton(), $this->renderDropdown()]);
     }
 }