We have a RadTreeView with "Visibility" property set to "Hidden". We add dynamically RadTreeViewItems to the RadTreeView. If we change the "Visibility" to "Visible" - the RadTreeView is NOT displayed. Originally this item is logged for scenario with XBAP. Currently we are unable to reproduce such issue with WPF 4.0 and latest version of our controls. Please open a new support thread if you encounter similar issues at your side.