http://blogs.labo-dotnet.com/simon/archive/2006/10/06/11250.aspx

Flip-3D is directly built in the core of the composition engine. It has access to much more features than I have, using public APIs. Flip-3D do not use DWM thumbnails. It simply applies 3D transform Matrices to the windows. This is a thing I cannot do. So I cannot manipulate the windows directly, and if I hide them, they are not redrawing anymore, and my thumbnail are not "live".