private function check_authorizations(ShoutboxMessage $message)
 {
     if (!$message->is_authorized_to_delete()) {
         $error_controller = PHPBoostErrors::user_not_authorized();
         DispatchManager::redirect($error_controller);
     }
     if (AppContext::get_current_user()->is_readonly()) {
         $controller = PHPBoostErrors::user_in_read_only();
         DispatchManager::redirect($controller);
     }
 }