Button::setProperty

protected function setProperty($propertyName, $value, $enum)
{
	if ($this->isEnumValue($value, $enum))
	{
		$this
			->removeClass($this->getProperty($propertyName))
			->addClass($value)
		;
		$this->properties[$propertyName] = $value;
	}
	elseif ($value === null)
	{
		$this->removeClass($this->getProperty($propertyName));
		$this->properties[$propertyName] = $value;
	}

	return $this;
}