private void AcceptedResponses_ItemsCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) { _model.ModifyAcceptedResponsesCollection(col => ObservableCollectionHelper.ApplyChangesByObjects <DriverResponseLogic, DriverResponseModel>(e, col, l => l.Model, l => l.Model)); if (e.NewItems != null) { foreach (DriverResponseLogic response in e.NewItems.OfType <DriverResponseLogic>().ToArray()) { response.ResponseAuthor.Model.HasAcceptedRequest = true; } } if (e.OldItems != null) { foreach (DriverResponseLogic response in e.OldItems.OfType <DriverResponseLogic>().ToArray()) { response.ResponseAuthor.Model.HasAcceptedRequest = true; } } }