In VS 2010 created a new WinForm project. Added a new UserControl WPF.
WinForm
2 compile-time errors appeared:
Error 1 The type \'Sys
it sounds like you just need a reference to System.Xaml.dll
System.Xaml.dll
Re whether this is a bug in VS; well, I suppose the templates could add that reference - I can reproduce it, so it may be worth logging on connect