When working with the selection of the RadTreeView control you should keep in mind that there are some known limitations regarding the RadTreeView.SelectedItem and RadTreeView.SelectedItems properties. This is why we suggest using the IsSelected property of the RadTreeViewItem. You can take advantage of it by exposing a boolean property in your ViewModel and binding it using a custom Style targeting the RadTreeViewItem control.
I used our documentation article to create a sample project which takes advantage of the XML DataProvider. I exposed the boolean IsSelected property in the XmlNodeItem class and its setter I update a static property holding the business object behind the selected RadTreeViewItem. This approach is demonstrated in the attached project. Please take a look at it and let me know if you need any further assistance.
Pavel R. Pavlov
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