Test the interactivity of triggers in WPF controls
If your Microsoft Expression Blend project includes a storyboard that runs in response to a trigger, you can verify that the trigger initiates the storyboard and see how the storyboard behaves in your application.
To test the interactivity of triggers
With your project open in Microsoft Expression Blend, click Test Project on the Project menu or press F5. If the test build is successful, your project automatically opens in an application window and you can verify whether your animation behaves correctly.