public static string FormatMessage([NotNull] string message, [NotNull] MessageFlags messageFlags, bool targetBlankOverride, DateTime messageLastEdited)
    {
      ...
      // do html damage control
      message = RepairHtml(message, messageFlags.IsHtml);

      //Process hidden tag replacement. - //Tommy
      {
        bool isUserAdmin = YafContext.Current.IsAdmin;

        Match hiddenTagMatch = _rgxHidden.Match(message);
        if (hiddenTagMatch.Success)
        {
          Group hiddenContent = hiddenTagMatch.Groups["hiddencontent"];
          //TODO: Get "shownContent" from configuration so an admin can change w/o recompiling.
          string shownContent = "<div class='Warning'style='width:670px;'>" +
            "<div style='float:right; padding-top:10px;'><img src='http://forum.tkaraoke.com/images/ThankYouPost.png' /></div>" +
            "The content of this page is hidden. After you THANK the poster, refresh the page to see the hidden content. You only need to thank the first post (post #1).<br /><br />" +
            "Phần nội dung đã bị ẩn đi. Sau khi nhấn vào nút THANK để cám ơn người đăng bài này, bạn phải Refresh trang này lại để thấy nội dung. Bạn chỉ cần THANK <span style='text-decoration:underline; font-weight:bold;'>post đầu tiên</span> (post #1 ở trang 1)." +
            "</div>";
          if (isUserAdmin)
          {
            shownContent = hiddenContent.Value;
          }
          else if (YafContext.Current.User != null &&
                   YafContext.Current.User.IsApproved)
          {
            int userId = YafContext.Current.CurrentUserData.UserID;
            int topicId = YafContext.Current.PageTopicID;
            if ((GetTopicStarter(topicId) == userId) ||
               (IsUserThankedTopicStarter(topicId, userId)))
            {
              //Show hiddent content if user is the poster or have thanked the poster.
              shownContent = hiddenContent.Value;
            }
          }

          //Update the hidden content with the updated content.
          message = _rgxHidden.Replace(message, shownContent);
        }
      }
...

    public static int GetTopicStarter(int topicId)  //Tommy
    {
      try
      {
        string query = "SELECT UserID FROM yaf_Topic WHERE TopicID=" + topicId;
        using (var cmd = new System.Data.SqlClient.SqlCommand(query))
        {
          cmd.CommandType = CommandType.Text;
          int userId = (int)YafDBAccess.Current.ExecuteScalar(cmd);
          return userId;
        }
      }
      catch (Exception)
      {
        return -1;
      }
    }

    public static bool IsUserThankedTopicStarter(int topicId, int userId)  //Tommy
    {
      System.Text.StringBuilder querySb =
        new System.Text.StringBuilder();
      querySb.Append("SELECT COUNT(TH.ThanksID) ");
      querySb.Append("FROM yaf_Message AS M INNER JOIN ");
      querySb.Append("yaf_Topic AS T ON M.TopicID = T.TopicID INNER JOIN ");
      querySb.Append("yaf_Thanks AS TH ON M.MessageID = TH.MessageID ");
      querySb.Append("WHERE (T.TopicID = {0}) AND (M.Position = 0) AND (TH.ThanksFromUserID = {1})");
      string query = string.Format(querySb.ToString(),
        topicId, userId);

      using (var cmd = new System.Data.SqlClient.SqlCommand(query))
      {
        cmd.CommandType = CommandType.Text;
        int thankCount = (int)YafDBAccess.Current.ExecuteScalar(cmd);
        return (thankCount > 0);
      }
    }

    /// <summary>
    /// The regular expression to process [hidden]...[/hidden]
    /// </summary>
    private static readonly Regex _rgxHidden =
      new Regex(@"\[hidden\](?<hiddencontent>(.*?))\[/hidden\]", _options |
        RegexOptions.Singleline | RegexOptions.Compiled);  //Tommy

[HIDDEN]...[HIDDEN]

[HIDDEN=123]...[HIDDEN]

 
// Remove HIDDEN Text
message = this.Get<IFormatMessage>().RemoveHiddenBBCodeContent(message);

protected override void Render(HtmlTextWriter writer)
        {
            var hiddenContent = Parameters["inner"];

            var messageId = this.MessageID;

            if (hiddenContent.IsNotSet())
            {
                return;
            }