public function setInfo($message, $details = "", $auto_hide = false)
    {
        if (empty($message)) {
            return;
        }
        
        // we keep messages in the session
        // until we are sure they are shown
        // otherwise some messages may be lost
        // because of redirection
        self::$session_vars["infos"][$message] = [
            "message" => $message,
            "details" => $details,
            "auto_hide" => $auto_hide
        ];
    }