Nodes not updated when hierarchy are changed

[Kenneth]

I make a treelistview with an itemssource that contains two List items.

 

When I push a button, I move the last item in as a child on the first item.

But to get this to work, I need to:

radTreeListView.ItemsSource = null;
radTreeListView.ItemsSource = source;

This operation takes 600 ms when working with 1.000 rows so it is not desirable.

 

I have tried to make the List item in to an ObservableCollection but with no luck.

 

Are there any suggestion to an alternative handling?

The XAML:

 

<Grid>
        <telerik:RadTreeListView x:Name="radTreeListView" AutoGenerateColumns="False">
            <telerik:RadTreeListView.ChildTableDefinitions>
                <telerik:TreeListViewTableDefinition ItemsSource="{Binding Children}" />
            </telerik:RadTreeListView.ChildTableDefinitions>
            <telerik:RadTreeListView.Columns>
                <telerik:GridViewDataColumn DataMemberBinding="{Binding Name}" Header="Name" />
            </telerik:RadTreeListView.Columns>
        </telerik:RadTreeListView>
    </Grid>

The code behind:

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            List<Item> itemList = new List<Item>();
            itemList.Add(new Item("Drink"));
            this.radTreeListView.ItemsSource = itemList;

            radTreeListView.Loaded += delegate(object sender, RoutedEventArgs e)
            {
                List<Item> source = ((List<Item>)radTreeListView.ItemsSource);
                source.First().Children.Add(new Item("Carrot"));

                //This works but takes time when I have 1.000 posts:
                radTreeListView.ItemsSource = null;
                radTreeListView.ItemsSource = source;

                //Refresh radTreeListView
                radTreeListView.Rebind();
            };
        }
    }

    public class Item
    {
        public Item(string name)
        {
            this.Name = name;
            this.Children = new List<Item>();
        }

        public string Name { get; set; }

        public List<Item> Children { get; set; }
    }

[Kenneth]

I just had to set the child as an observableCollection instead of setting it as a List:

public ObservableCollection<Item> Children { get; set; }