src/Widgets/Bootstrap/ButtonDropdown.php
public function run()
    {
        unset($this->options['id']);
        Html::addCssClass($this->options, ['widget' => 'btn-group']);
        if ($this->dropUp) {
            Html::addCssClass($this->options, 'dropup');
        }
        $options = $this->options;
        $tag = ArrayHelper::remove($options, 'tag', 'div');

        $this->registerPlugin('dropdown');
        return implode("\n", [
            $this->htmlHlp->beginTag($tag, $options),
            $this->renderButton(),
            $this->renderDropdown(),
            $this->htmlHlp->endTag($tag)
        ]);
    }
public function run()
    {
        unset($this->options['id']);
        Html::addCssClass($this->options, ['widget' => 'btn-group']);
        if ($this->dropUp) {
            Html::addCssClass($this->options, 'dropup');
        }
        $options = $this->options;
        $tag = ArrayHelper::remove($options, 'tag', 'div');

        $this->registerPlugin('dropdown');
        return implode("\n", [
            $this->htmlHlp->beginTag($tag, $options),
            $this->renderButton(),
            $this->renderDropdown(),
            $this->htmlHlp->endTag($tag)
        ]);
    }
Renders the widget.