Binding "SelectedItems" of a Listbox

[Jayme65]

Hi, Could you please help me figure out how I could bind "SelectedItems" of a listbox? Here I have a 'listbox_2' that contains a list of fruits and vegetables ;) There's another 'listbox_1' that contains groups of fruits and vegetables (under a list format...maybe is it my first error? Should it rather be a list of fruits/vegetables?) and a recipe. I would like that on each group selection (in listbox_1), the corresponding fruits and vegetables would be selected (in listbox_2)...and make it possible to modify that list https://i.imgur.com/nENJTCY.jpg Unfortunately, the way to achieve this behavior stays obscure to me...could you please help? Here's what I've set up untill now: C#

public partial class MainWindow : Window
{
ItemList il;
GroupList gl;

    public MainWindow()
    {
        InitializeComponent();
    }
    private void Window\_Loaded(object sender, RoutedEventArgs e)
    {
        il = new ItemList();
        ICollectionView cvs = CollectionViewSource.GetDefaultView(il);
        cvs.SortDescriptions.Add(new SortDescription("\_type", ListSortDirection.Ascending));
        cvs.SortDescriptions.Add(new SortDescription("\_name", ListSortDirection.Ascending));
        cvs.GroupDescriptions.Add(new PropertyGroupDescription("\_type"));
        ListBox2.ItemsSource = cvs;

        gl = new GroupList();
        ICollectionView cvt = CollectionViewSource.GetDefaultView(gl);
        ListBox1.ItemsSource = cvt;
    } 
}

public class Item
{
    public string \_type { get; set; }
    public string \_name { get; set; }
    public Item()
    {
    }
}
public class ItemList : ObservableCollection {
    public ItemList() {
        base.Add(new Item() { \_type = "fruit", \_name = "apple" });
        base.Add(new Item() { \_type = "vegetable", \_name = "potato" });
        base.Add(new Item() { \_type = "fruit", \_name = "banana" });
        base.Add(new Item() { \_type = "vegetable", \_name = "tomato" });
        base.Add(new Item() { \_type = "fruit", \_name = "pear" });
        base.Add(new Item() { \_type = "vegetable", \_name = "salad" });
        base.Add(new Item() { \_type = "fruit", \_name = "orange" });
        base.Add(new Item() { \_type = "vegetable", \_name = "onion" }); 
    }
}

public class Group
{
    public string \_groupname { get;

[Lost User]

[How to: Use the Master-Detail Pattern with Hierarchical Data | Microsoft Docs](https://docs.microsoft.com/en-us/dotnet/framework/wpf/data/how-to-use-the-master-detail-pattern-with-hierarchical-data)

"(I) am amazed to see myself here rather than there ... now rather than then". ― Blaise Pascal