/// <summary>
        /// Adds a new item value by copying an existing one.
        /// </summary>
        private void CopyMI_Click(object sender, System.EventArgs e)
        {
            try
            {
                // check for valid selection.
                if (ReadOnly || valuesLv_.SelectedItems.Count != 1)
                {
                    return;
                }

                TsCHdaItemValue value = (TsCHdaItemValue)valuesLv_.SelectedItems[0].Tag;

                // create new item value.
                TsCHdaItemValue copy = new ItemValueEditDlg().ShowDialog((TsCHdaItemValue)value.Clone());

                // prompt user to edit item value.
                if (copy == null)
                {
                    return;
                }

                // update display.
                AddListItem(copy, valuesLv_.SelectedIndices[0]);

                // adjust columns
                AdjustColumns();
            }
            catch (Exception exception)
            {
                MessageBox.Show(exception.Message);
            }
        }
        /// <summary>
        /// Adds a new test case by copying an existing one.
        /// </summary>
        private void CopyMI_Click(object sender, System.EventArgs e)
        {
            try
            {
                // check for valid selection.
                if (ValuesLV.SelectedItems.Count != 1)
                {
                    return;
                }

                TsCHdaItemValue value = (TsCHdaItemValue)ValuesLV.SelectedItems[0].Tag;

                // create new item value.
                TsCHdaItemValue copy = new ItemValueEditDlg().ShowDialog((TsCHdaItemValue)value.Clone());

                // prompt user to edit test case.
                if (copy == null)
                {
                    return;
                }

                // update display.
                AddItem(copy, false);
            }
            catch (Exception exception)
            {
                MessageBox.Show(exception.Message);
            }
        }