Can I adjust RadDocking so that I would be able to place RadPane into one (tabbed) or a few RadPaneGroups, but within the same DocumentHost?

For example:

write:

1. Cancel Selection
   The ItemsSource property is bound to a collection containing A and B objects. I want that only the A object are selectable. The B objects are just for information. I use the following code:
   

   void radTreeView_PreviewSelected(object sender, Telerik.Windows.RadRoutedEventArgs e)

   {

   // get a reference to the item that will be selected

   RadTreeViewItem itemToSelect = e.OriginalSource as RadTreeViewItem;

   // check item that will be selected

   if (itemToSelect != null && itemToSelect.Item is B)

   {

   e.Handled = true;

   }

   }

   However, the SelectedItem property contains the B object afterwards. I would expect the SelectedItem property to be null.
2. Remove the selected item from the bound collection
   If I remove the currently selected item from the bound collection, then the node has disappeard as I expected, but the SelectedItem property still contains the removed object. I would expect, that the SelectedItem property always contains objects that are also in the ItemsCollection or null otherwise.