Occurs when the user selects a file name by either clicking the Open button of the OpenFileDialog or the Save button of the SaveFileDialog.
public event CancelEventHandler FileOk
FileOk is raised after the user selects a file name, but before the dialog closes, which allows you to process the selection. If required, the user's selection can be cancelled by setting the Cancel property of the CancelEventArgs argument to true.
FileDialog ClassMicrosoft.Win32 Namespace