private void MenuItem_Checked_Area(object sender, RoutedEventArgs e) { var AreaMenuItem = (sender as MenuItem).Parent as MenuItem; foreach (MenuItem item in AreaMenuItem.Items) { if (item.Header != (sender as MenuItem).Header) { item.IsChecked = false; } } if (((string)(sender as MenuItem).Header) == "הכל") { MainListBox.ItemsSource = Requests; return; } BO.Location selectedLocation = (BO.Location)MyDictionary.TranslatStringeToEnum((string)(sender as MenuItem).Header); MainListBox.ItemsSource = from Group in bl.GuestRequestGroupedBySpecificArea() where Group.Key == selectedLocation select Group into items from guestRequest in items where guestRequest.ClientID != hostID select guestRequest; }