It's easier to demonstrate in this video:
http://screencast.com/t/r1G7UpzV

The test was recorded against this WPF UI Controls demo app:
http://demos.telerik.com/wpf/

The test log shows:
Overall Result: Fail
------------------------------------------------------------
'5/21/2015 7:07:37 PM' - Executing test: 'Scratch WPF Test', path: 'Scratch WPF Test.tstest.'
'5/21/2015 7:07:37 PM' - Using .Net Runtime version: '4.0.30319.34209' for test execution. Build version is '2015.1.515.0'.
'5/21/2015 7:07:37 PM' - Starting execution....
'5/21/2015 7:07:39 PM' - Detected custom code in test. Locating test assembly: TestExamplesProject.dll.
'5/21/2015 7:07:39 PM' - Assembly Found: E:\Users\Dad\Documents\Test Studio Projects\TestExamplesProject\bin\TestExamplesProject.dll
'5/21/2015 7:07:39 PM' - Loading code class: 'TestExamplesProject.Scratch_WPF_Test'.
------------------------------------------------------------
------------------------------------------------------------
'5/21/2015 7:07:39 PM' - Using 'E:\Users\Dad\AppData\Local\Apps\2.0\M69B0QX7.GCQ\Z3LEK3TZ.4LW\wpfd..tion_8da4a4c959549401_07df.0001_cbd4928d07320de5\WPF Demos.exe' application.
'5/21/2015 7:07:41 PM' - 'Pass' : 1. LeftClick on Item16Textblock
'5/21/2015 7:07:44 PM' - 'Pass' : 2. LeftClick on SmallNameTextblock
'5/21/2015 7:07:47 PM' - 'Pass' : 3. LeftClick on TreeViewTextblock
'5/21/2015 7:07:51 PM' - 'Pass' : 4. LeftClick on CustomTextblock
'5/21/2015 7:07:53 PM' - 'Pass' : 5. RightClick on TreeViewXamlTextblock
'5/21/2015 7:07:54 PM' - 'Fail' : 6. radmenuitem: 'Delete' click action.
------------------------------------------------------------
Failure Information: 
~~~~~~~~~~~~~~~
Unable to find the specified element: Unable to find the element of type: 
InnerException:
ArtOfTest.Common.Exceptions.FindElementException: Unable to find the specified element: Unable to find the element of type: 
   at ArtOfTest.WebAii.Wpf.WpfProxy.ExecuteSLCommand(SilverlightCommand cmd)
   at ArtOfTest.WebAii.Wpf.WpfProxy.GetProperty(AutomationProperty property, IAutomationPeer peer)
   at ArtOfTest.WebAii.Silverlight.AutomationObject`1.GetProperty(AutomationProperty property)
   at ArtOfTest.WebAii.Controls.Xaml.Wpf.Popup.get_IsOpen()
   at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.get_ItemElements()
   at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.WaitForSubItemsPopupAnimation()
   at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.Click()
   at Telerik.WebAii.Design.Translators.Xaml.Menu.ItemClickAction.Execute(IApplication appHost)
   at ArtOfTest.WebAii.Design.Extensibility.XamlActionDescriptor.Execute(IAutomationHost autoHost)
   at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)
------------------------------------------------------------
'5/21/2015 7:07:54 PM' - Detected a failure. Step is marked 'ContinueOnFailure=False' aborting test execution.
------------------------------------------------------------
'5/21/2015 7:07:54 PM' - Overall Result: Fail
'5/21/2015 7:07:54 PM' - Duration: [0 min: 14 sec: 883 msec]
------------------------------------------------------------
'5/21/2015 7:07:56 PM' - Test completed!

The Test Studio application log contains this:
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),Execution] ExecutionEngine.NotifyAfterStepExecuted() : Finished executing step 5 "RightClick on TreeViewXamlTextblock".
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::Start
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::End
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.SetCurrentStep() : VisualDebugger::SetCurrentStep
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::Start
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::End
[05/21 19:15:46,ArtOfTest.Runner.exe(85972:11),Framework] Manager.get_ActiveBrowser() : The current ActiveBrowser is either invisible or disconnected.
[05/21 19:15:47,ArtOfTest.Runner.exe(85972:5),Execution] ExecutionEngine.NotifyBeforeStepExecuted() : Executing step 6 "radmenuitem: 'Delete' click action."...
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Error] ExecutionEngine.CatchExecuteStepException() : EXCEPTION! (see below)
     Outer Exception Type: ArtOfTest.Common.Exceptions.FindElementException
     Message: Unable to find the specified element: Unable to find the element of type:
     HRESULT: 0x80131500 (Official ID (if app.) = COR_E_EXCEPTION, Error Bit = FAILED, Facility = FACILITY_URT, Code = 5376)
     Call Stack:
          at ArtOfTest.WebAii.Wpf.WpfProxy.ExecuteSLCommand(SilverlightCommand cmd)
          at ArtOfTest.WebAii.Wpf.WpfProxy.GetProperty(AutomationProperty property, IAutomationPeer peer)
          at ArtOfTest.WebAii.Silverlight.AutomationObject`1.GetProperty(AutomationProperty property)
          at ArtOfTest.WebAii.Controls.Xaml.Wpf.Popup.get_IsOpen()
          at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.get_ItemElements()
          at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.WaitForSubItemsPopupAnimation()
          at Telerik.WebAii.Controls.Xaml.Wpf.RadMenuItem.Click()
          at Telerik.WebAii.Design.Translators.Xaml.Menu.ItemClickAction.Execute(IApplication appHost)
          at ArtOfTest.WebAii.Design.Extensibility.XamlActionDescriptor.Execute(IAutomationHost autoHost)
          at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)

[05/21 19:15:48,ArtOfTest.Runner.exe(85972:11),Framework] Manager.get_ActiveBrowser() : The current ActiveBrowser is either invisible or disconnected.
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:11),Framework] Manager.get_ActiveBrowser() : The current ActiveBrowser is either invisible or disconnected.
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::BreakOnFail
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.CheckPause() : VisualDebugger::CheckPause::End
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.ShutDown() : VisualDebbuger::ShutDown::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Uncategorized] AdornerWindow.ShutDown() : AdornerWnd::ShutDown::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Uncategorized] AdornerWindow.ShutDown() : AdornerWnd::DetachWrappedWindow::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Uncategorized] AdornerWindow.ShutDown() : AdornerWnd::DetachWrappedWindow::End
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Uncategorized] AdornerWindow.ShutDown() : AdornerWnd::DispatcherBeginInvokeShutdown::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Uncategorized] AdornerWindow.ShutDown() : AdornerWnd::Close::Start
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),TestStudio] VisualDebugger.ShutDown() : VisualDebbuger::ShutDown::End
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Framework] BrowserProvisioner.EndService() : Connecting to the provisioning pipe "Pipe.ArtOfTest.WebAii.BrowserProvisioner_1221164139" in order to unblock and eventually terminate it...
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:8),Framework] BrowserProvisioner.ServiceThread() : A new client has connected to the provisioning pipe but this will be treated as a termination cue.
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Framework] BrowserProvisioner.EndService() : Provisioning pipe connected.
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Framework] BrowserProvisioner.EndService() : Provisioning thread terminated.
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),DialogPlayback] DialogMonitor.Stop() : Dialog monitoring is being halted.
[05/21 19:15:48,WPF Demos.exe(76516:10)] First trace message from background thread "Client command listener thread" (managed ID = 10, native ID = 88000).
[05/21 19:15:48,WPF Demos.exe(76516:10),Framework] BrowserRemoteClient.Disconnect() : Sending ClientDisconnectRequest(ClientId="Client_15d26176-bd3f-4f67-8f61-f34a0fdfd593") to pipe server...
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Warning] Manager.RemoveBrowser() : Attempted to remove a client ID "Client_15d26176-bd3f-4f67-8f61-f34a0fdfd593" that was not in the list.
[05/21 19:15:48,WPF Demos.exe(76516:10),Framework] BrowserRemoteClient.Disconnect() : Disconnecting command pipe (Handle = 1700).
[05/21 19:15:48,ArtOfTest.Runner.exe(85972:5),Framework] BrowserRemoted.End() : Now aborting the listener thread (TID = 9).
[05/21 19:15:50,ArtOfTest.Runner.exe(85972:5),Framework] WpfApplication.Detach() : Process killed (ID=76516, ExitCode=259, Path="E:\Users\Dad\AppData\Local\Apps\2.0\M69B0QX7.GCQ\Z3LEK3TZ.4LW\wpfd..tion_8da4a4c959549401_07df.0001_cbd4928d07320de5\WPF Demos.exe", Arguments="").
[05/21 19:15:50,ArtOfTest.Runner.exe(85972:12)] First trace message from background thread "MS UI Automation event queue processor" (managed ID = 12, native ID = 87636).
[05/21 19:15:50,ArtOfTest.Runner.exe(85972:12),Warning] Manager.RemoveBrowser() : Attempted to remove a client ID "Client_15d26176-bd3f-4f67-8f61-f34a0fdfd593" that was not in the list.
[05/21 19:15:50,ArtOfTest.Runner.exe(85972:12),Framework] BrowserRemoted.End() : Now aborting the listener thread (TID = 9).
[05/21 19:15:50,Telerik.TestStudio.exe(82480:51)] First trace message from background thread "Callback Listener Thread" (managed ID = 51, native ID = 87856).
[05/21 19:15:50,Telerik.TestStudio.exe(82480:51),Warning] PipeCommunication.SyncPipeRead() : Pipe was already disposed at the moment of the read attempt.