public int IndexOf(object value)
        {

            int index = CustomRows.IndexOf(value);
            if (index == -1)
                return NestedList.IndexOf(value);
            return index + NestedList.Count;
        }
 /// <summary>
 /// Add custom row to current table
 /// </summary>
 /// <param name="customRow">custom row to add</param>
 public void AddCustomRow(CustomRow <TableItem> customRow)
 {
     CustomRows.Add(customRow);
 }
 public bool IsCustomItem(object value)
 {
     return CustomRows.Contains(value);
 }