SubButton::init

protected function init(array $params = [])
{
	$this->removeClass($this->getBaseClass());

	if (!empty($params['buttonType']))
	{
		$this->buttonType = $params['buttonType'] === Type::MAIN? Type::MAIN : Type::MENU;
	}

	$this->baseClass = $this->buttonType;
	parent::init($params);

	if ($this->isInputType())
	{
		throw new NotSupportedException("Split button cannot be an input tag.");
	}
}