title: .NET 4.0 - Microsoft.Windows.Shell - where is it?
body: <p>I'm playing around with the examples for the Sofa V2.5, which is a WPF Docking framework.</p>
  
  <p>These are VS2010, .NET 4.0.  In one project, there's a reference to a "Microsoft.Windows.Shell" assembly, which is unresolved.</p>
  
  <p>When I open the Add Reference and look for .NET assemblies, I don't see Microsoft.Windows.Shell.  Why not?  I'm running VS2010 on Windows 7.  How can it be missing?  If it's not missing, why can't VS2010 see it?</p>