/// <summary>
        /// Handles the Click event of the edit columnizer <see cref="Button"/>.
        /// </summary>
        private void BtnEditColumnizerClick(object sender, EventArgs e)
        {
            using (FrmColumnizer columnizerDlg = new FrmColumnizer(cmbColumnizer.SelectedItem as Columnizer))
              {
            if (columnizerDlg.ShowDialog(this) == DialogResult.OK)
            {
              int changedItemIndex = cmbColumnizer.Items.IndexOf(columnizerDlg.Columnizer);

              if (changedItemIndex != -1)
              {
            cmbColumnizer.Items.RemoveAt(changedItemIndex);

            cmbColumnizer.Items.Insert(
                changedItemIndex
              , columnizerDlg.Columnizer);

            cmbColumnizer.SelectedItem = columnizerDlg.Columnizer;
              }

              // Refresh the possible changed columnizer list in case the name of the selected item has been changed.
              cmbColumnizer.Refresh();

              // Save the changed columnizer list.
              SaveColumnizer();
            }
              }

              UpdateEditButtons();
        }
        /// <summary>
        /// Handles the Click event of the add columnizer <see cref="Button"/>.
        /// </summary>
        private void BtnAddColumnizerClick(object sender, EventArgs e)
        {
            using (FrmColumnizer columnizerDlg = new FrmColumnizer())
              {
            if (columnizerDlg.ShowDialog(this) == DialogResult.OK && columnizerDlg.Columnizer != null)
            {
              // Add the new item to the selection list.
              cmbColumnizer.Items.Add(columnizerDlg.Columnizer);

              // Select it a new default.
              cmbColumnizer.SelectedItem = columnizerDlg.Columnizer;

              // Save the changed columnizer list.
              SaveColumnizer();
            }
              }

              UpdateEditButtons();
        }