private void _addToolButton_Click(object sender, EventArgs e) { using (var extAdder = new FileExtensionAdder()) { var dialogRes = extAdder.ShowDialog(this); if (dialogRes != DialogResult.OK) { var fileExt = extAdder.GetFileExtension(); var fileProvider = new FileProvider(); var persister = new FileExtensionPersister(fileProvider); persister.SaveFileExtensions(fileExt); } } }