please add..
#define THREAD_MODE_BACKGROUND_BEGIN 0x00010000
#define THREAD_MODE_BACKGROUND_END 0x00020000
In /include/winbase.h
Just next to the other THREAD_PRIORITY_* defines.
you can confirm the above definitions via MSDN.
i manually added them to my headers, and everything compiles fine. They are only ever passed to SetThreadPriority() just like THREAD_PRIORITY_* defines are.
Fix will be included in next release.