Visual Studio 2010 Silverlight quirk?

I have been messing around with Visual Studio 2010 RC and I noticed that if I create a new Silverlight project and add a button or a text box that nothing is displayed when I run my program. If I upgraded an existing Visual Studio 2008 Silverlight project to Visual Studio 2010 everything displayed normally. What is going on? I found that looking at the MainPage.xaml the 2008 Silverlight project had two lines that the 2010 Silverlight project did not. I added those two lines to the 2010 Silverlight and it started working. These are the lines I added:


xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
xmlns:uriMapper="clr-namespace:System.Windows.Navigation;assembly=System.Windows.Controls.Navigation"

I also added a reference to System.Windows.Controls.Navigation.

Any comments? Anyone else seen this problem?