Just so you know, DwmIsCompositionEnabled always return TRUE on Windows 8. So it shouldn't be that much of a problem only setting *enabled to TRUE.
Thank you, I forgot to check MSDN's documentation before writing the patch. I've submitted v3.
You should also consider implementing DwmEnableComposition
According to MSDN however, DwmEnableComposition has no effect under Windows 8?
As for the others, I agree, I'll try to get around to it if I can find more programs using it to test. Enabling it will cause some programs to assume various functions will exist, so I think at least stubbing the DLL is likely going to be important.
Thanks for the review.