Triggers and user interactivity
During an application's lifetime, objects in the user interface undergo changes to their state. State is often expressed in terms oriented toward the user. For example, a button’s mouse-over state, or a menu item’s pressed state. These two example states are implemented on objects by using the UIElement.IsMouseOver property and the MenuItem.IsPressed property, respectively. You can configure your application to respond to the change in a trigger, for example, to run an animation.
Triggers are not supported in Microsoft Silverlight 1.0 or Silverlight 2 projects. All user interaction in a Silverlight 1.0 application is accomplished by using event handlers. For an example, see Create a button that controls a storyboard in a Silverlight application. User interaction in a Silverlight 2 application can be accomplished by using event handlers or states. For more information, see Change state in response to user interaction.