src/Widgets/Bootstrap/Button.php
public function init()
    {
        parent::init();
        $this->clientOptions = false;
        $this->htmlHlp->addCssClass($this->options, ['widget' => 'btn']);
    }
public function init()
    {
        parent::init();
        $this->clientOptions = false;
        $this->htmlHlp->addCssClass($this->options, ['widget' => 'btn']);
    }
Initializes the widget.
If you override this method, make sure you call the parent implementation first.