Hello paul orsillo,
RadTreeListView, as well as all of its satellite types (such as TreeListViewTableDefinition), are located in the Telerik.Windows.Controls.GridView assembly and should be accessible from the xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" namespace in XAML. Please let me know if you would like me to prepare a very simple sample project for you.
All the best,
the Telerik team
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