protected override void OnClosing(CancelEventArgs e)
{
// Prevent user from closing by using the close button or close method
e.Cancel = true;
// Generate event so handlers to perform appropriate processing
string[] uniqueNames = VisibleCloseableUniqueNames();
if (uniqueNames.Length > 0)
OnWindowCloseClicked(new UniqueNamesEventArgs(uniqueNames));
base.OnClosing(e);
}