protected function canUpdate() {        
        $user_id = Filter::postInteger('userid', -1) ?: Filter::getInteger('userid', -1);
        return Auth::check() && 
            ( 
                $user_id == Auth::user()->getUserId() ||        // Allow update for yourself
                ($user_id == -1 && Auth::isManager(Globals::getTree()))   // Allow a manager to update the default user
             );
    }