I have a ListBox bound to an AsyncDataSourceProvider with data virtualization enabled. In the SelectionChanged event, the SelectedItem is null, the SelectedValue is null, and the SelectedItems is empty.

I am aware of Marc's blog post explaining how to get the selected items from a virtualized DataGrid, but it doesn't work with the ListBox.

How do I retrieve the selected item or items from the ListBox in this scenario?

Never mind - I've just found it.

private void ListBox_SelectionChanged(object sender, EventArgs e)
{
    var list = (Xceed.Silverlight.ListBox.ListBox)sender;
    list.BeginGetSelectedItems(ar =>
    {
        IEnumerable<object> items = list.EndGetSelectedItems(ar);
        // Use selection here...
    }, null);
}