public function registerPage(ServerRequestInterface $request): ResponseInterface
    {
        $this->checkRegistrationAllowed();

        $comments = $request->get('comments', '');
        $email    = $request->get('email', '');
        $realname = $request->get('realname', '');
        $username = $request->get('username', '');

        $show_caution = Site::getPreference('SHOW_REGISTER_CAUTION') === '1';

        $title = I18N::translate('Request a new user account');

        return $this->viewResponse('register-page', [
            'comments'     => $comments,
            'email'        => $email,
            'realname'     => $realname,
            'show_caution' => $show_caution,
            'title'        => $title,
            'username'     => $username,
        ]);
    }