Huge issue with breaking changes in beta 2 for loading xaml for controls.
The breaking changes page says to change this code:
System.IO.Stream s = this.GetType().Assembly.GetManifestResourceStream("MyNamespace.UserControl1.xaml");
root = this.InitializeFromXaml(new System.IO.StreamReader(s).ReadToEnd());
Application.LoadComponent( Go to the complete details ...