code: public function changeAction()
      {
          $theme = $this->container->get('request')->request->get('admin_theme');
          $this->container->get('vince_t.admin.theme.handler')->setCurrentTheme($theme);
          $headers = $this->container->get('request')->server->getHeaders();
          $referer = $headers['REFERER'];
          return new RedirectResponse($referer);
      }
docs: Change the current theme used
  
  @return RedirectResponse