test.cs

private bool MergeSimilarCells(TXTextControl.Table table, bool firstIteration = true) {
			
  // loop through all column separately
  foreach (TXTextControl.TableColumn col in table.Columns) {

    bool bMergeFlag = false;
    int iFirstRow = 0;
    string sCommonCellText = "";

    // row by row
    for (int row = 1; row <= table.Rows.Count; row++) { 

      // only cells that are not merged
      if (table.Cells[row, col.Column].Length != -1) {

        // if table cell contains text from previous cell
        // set "bMergeFlag" to true and flag row number
        if (table.Cells[row, col.Column].Text == sCommonCellText) {
          if (bMergeFlag == false) iFirstRow = row;
          bMergeFlag = true;
        }
        // if text is different and "bMergeFlag" is true, merge cells
        else if (bMergeFlag == true) {
          MergeCells(table, iFirstRow - 1, col.Column, row - 1, col.Column, sCommonCellText);
          bMergeFlag = false;
        }

        // if flag "bMergeFlag" is true and it is the last row, merge cells
        if (bMergeFlag == true &&
          row == table.Rows.Count &&
          table.Cells[row, col.Column].Text == sCommonCellText) {
          MergeCells(table, iFirstRow - 1, col.Column, row, col.Column, sCommonCellText);
        }

        // remember current cell text
        if (row < table.Rows.Count)
          sCommonCellText = table.Cells[row, col.Column].Text;

      }

    }
  }

  // two iterations required as rows are potentially merged
  if (firstIteration == true)
    MergeSimilarCells(table, false);

  return false;
}

// this method simply merges given cells and sets the common cell text
private void MergeCells(
  TXTextControl.Table table,
  int startRow,
  int startColumn,
  int stopRow,
  int stopColumn,
  string newText) {

  table.Select(startRow, startColumn, stopRow, stopColumn);
  table.MergeCells();
  table.Cells[startRow, startColumn].Text = newText;
}