void TaskTitleCellDataFunc(CellLayout layout, CellRenderer cell, TreeModel model, TreeIter iter) { var item = model.GetValue (iter, (int)TaskColumn.Task) as Task; var ctext = cell as CellRendererText; ctext.Strikethrough = false; ctext.Text = String.Empty; if (item != null) { var text = item.Title; if (item.Completed) ctext.Strikethrough = true; ctext.Text = text; } }