table.cs

public static class TableExtender {
  public class TabRow {
    public List<CellInfo> cellInfos = new List<CellInfo>();
  }

  public class CellInfo {
    public byte[] Text { get; set; }
    public int Left { get; set; }
  }

  public static void ConvertToTabs(this Table table, TextControl textControl) {

    textControl.BeginUndoAction("Table to tab positions");

    // throw exceptions when conditions are not met
    if (table.NestedTables.Count > 0)
      throw (new Exception("Nested tables cannot be convertetd."));

    if (table.Columns.Count > 14)
      throw (new Exception("Tables with more than 14 columns cannot be converted to tab positions."));

    // create a new list of tab position rows to store positions and texts
    List<TabRow> tabRows = new List<TabRow>();

    // loop through all rows and create a TabRow object for each row
    for (int row = 1; row <= table.Rows.Count; row++) {

      TabRow tabRow = new TabRow();

      // loop through each column to store the text and position
      for (int col = 1; col <= table.Columns.Count; col++) {

        TableCell curCell = table.Cells.GetItem(row, col);
        byte[] cellText;
        curCell.Select();
        textControl.Selection.Length -= 1;
        textControl.Selection.Save(out cellText, BinaryStreamType.InternalUnicodeFormat);

        tabRow.cellInfos.Add(new CellInfo() { Text = cellText, Left = curCell.Position });
      }

      tabRows.Add(tabRow);
    }

    // set input position after table
    TableCell lastCell = table.Cells[table.Rows.Count, table.Columns.Count];
    textControl.InputPosition = new InputPosition(lastCell.Start + lastCell.Length);

    // loop through the created list to add the text at a new tab position 
    foreach (TabRow row in tabRows) {

      int[] tabPositions = textControl.Selection.ParagraphFormat.TabPositions;
      int colCounter = 0;

      foreach (CellInfo cell in row.cellInfos) {
        // tab positions cannot be 0
        tabPositions[colCounter] = cell.Left != 0 ? cell.Left : 1;
        // apply new tab position
        textControl.Selection.ParagraphFormat.TabPositions = tabPositions;
        textControl.Selection.Text = "\t"; // add tab character
        // load the stored text
        textControl.Selection.Load(cell.Text, BinaryStreamType.InternalUnicodeFormat);
        colCounter++;
      }

      // new row
      textControl.Selection.Text = "\r\n";

    }

    // remove the table
    textControl.InputPosition = new InputPosition(table.Cells[1, 1].Start);
    textControl.Tables.Remove();

    textControl.EndUndoAction();
  }
}