Prado\Web\UI\TThemeManager::setThemeClass PHP Метод

public setThemeClass ( string \| null $class )
$class	string \| null	Theme class name in namespace format

    public function setThemeClass($class)
    {
        $this->_themeClass = $class === null ? self::DEFAULT_THEMECLASS : (string) $class;
    }

TThemeManager