I am curently looking at the VISTA's DWMAPI.dll (Device Window Manager) to use the Skin Engine with it.
If ever you plan to work with it (dwmapi), I advise you that a good knowledge of GDIPLUS is a prerequisite, because all drawings must be done in full ARGB 32-bit mode, even the child controls drawn on the form when the client area is set to the transparent mode. And the BLUR mode takes a lot of CPU resources.
This is the reason why in zskin11 the blur mode is refreshed only each 500 millisecond to keep the CPU usage acceptable.