After configuring a Test Studio test to automate a Silverlight Out Of Browser application, the browser thinks it's running in-browser. Silverlight API calls that only work when running in Out Of Browser mode now fail. For example: This line of code returns false when it should return true: Application.Current.IsRunningOutOfßrowser This line of code throws an exception in the SL OOB application and will not run: Application.Current.MainWindow.WindowState WindowState.Maximized; Applications that rely heavily on such API calls cannot be automated by Test Studio's current SL OOB automation approach.