If a Silverlight application with a very large and busy UI that uses a ScrollViewer such that you MUST scroll vertically AND horizontally to get at all the input boxes will pretty much always not work and error out with something like this:
'9/26/2014 8:23:27 AM' - 'Fail' : 3. Type 'First box' into Textbox1Textbox
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Failure Information: 
~~~~~~~~~~~~~~~
Point (-472, 111) outside bounds of browser window: (0, 85, 1920, 965)
You might need to maxmize the browser while running this test. Try adding the following code in a coded step: ActiveBrowser.Window.Maximize();
InnerException:
System.InvalidOperationException: Point (-472, 111) outside bounds of browser window: (0, 85, 1920, 965)
You might need to maxmize the browser while running this test. Try adding the following code in a coded step: ActiveBrowser.Window.Maximize();
   at ArtOfTest.WebAii.Silverlight.SilverlightApp.ValidateMouseLocation(Point point)
   at ArtOfTest.WebAii.Silverlight.UserInteraction.Click(MouseClickType clickType, Point offsetPoint, OffsetReference reference)
   at ArtOfTest.WebAii.Silverlight.UserInteraction.Click(MouseClickType clickType)
   at ArtOfTest.WebAii.Controls.Xaml.XamlControlHelper.SetText(String propertyName, FrameworkElement xamlControl, Boolean simulateRealUser, String text, Int32 keyPressTime, Int32 keyHoldTime, Boolean fireKeyEvents, Boolean clearCurrentText)
   at ArtOfTest.WebAii.Silverlight.UI.TextBox.SetText(Boolean simulateRealUser, String text, Int32 keyPressTime, Int32 keyHoldTime, Boolean fireKeyEvents, Boolean clearCurrentText)
   at ArtOfTest.WebAii.Design.IntrinsicTranslators.Silverlight.Descriptors.TextBoxSetTextActionDescriptor.Execute(IApplication hostApp)
   at ArtOfTest.WebAii.Design.Extensibility.XamlActionDescriptor.Execute(IAutomationHost autoHost)
   at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)

Attached is a simple Silverlight app that mimics a real customers app (from ticket 854845). The customer is trying to run the test on a laptop which has a maximum resolution of 1366 x 768. Even after maximizing the browser, you still have to scroll horizontally and vertically to get at the input controls.

Also attached is a Test Studio test that tries to run against the attached Silverlight application. The Type Text steps MUST have SimulateRealUser checked because the customers real application requires this setting (it won't take the data otherwise).

What is really interesting is when the test runs the browser is scrolled all the way to the right (probably part of the Scroll To Visible action) actually causing the target input field to scroll off screen. You can NOT prevent this scrolling (without resorting to code). Now Test Studio tries to click on the target input field, but since the field is off screen you get an error and nothing is entered.