TreeView sample should show how to bind/retrieve selected items

[michael-hawker]

Is this a totally new sample, an addition to an existing sample page, or a modification of an existing sample page?

• New sample
• Addition to existing sample
• Modification to existing sample

If this is an addition/modification to an existing sample page, which one?
TreeViewPage

Is your sample request related to a problem? Please describe it
It is unclear how to retrieve the selected items from the TreeView control. It'd be great if the sample provided an example of how to programmatically retrieve and/or bind to the collection of SelectedItems.