private void ShowColumnList()
{
ColumnListBox.Items.Clear();
columnDefList.Sort();
foreach (ColumnDefinition colDef in columnDefList)
{
ColumnListBox.Items.Add(colDef);
int index = ColumnListBox.Items.IndexOf(colDef);
ColumnListBox.SetItemChecked(index, colDef.Visble);
}
}