When the RadTabControl is placed in a RadBusyIndicator, one of the navigation repeat buttons is initially disabled.
As a workaround, you can invoke the ScrollToHorizontalOffset method of the ScrollViewer inside the RadTabControl in a Dispatcher in the Loaded event:
The scroll buttons are not correctly displayed when the TabStripPlacement is set to Right and there is no default selection (the IsDefaultItemSelected is set to False). As a workaround set the RadTabControl's IsDefaultItemSelected property to True or select a RadTabItem manually through its IsSelected property.
In the TabControl Databinding example, the TabControl ItemTemplate contains Button controls that has to be replaced with RadButtons.