Get Your Silverlight MainPage

If you ever need to access the MainPage object of your Silverlight application (from elsewhere in that application), simply do this where needed:

MainPage mainPage = App.Current.RootVisual as MainPage;

Bonus Tip: Don't be hesitant to look at the code generated by Visual Studio. I found out wthat the RootVisual property represents the MainPage object and is set when the application is started. Once I discovered that, the rest was easy.