a couple bitwise nits in your first patch:

+#define HKCR_MASK 2

+#define IS_HKCR(hk) ((UINT_PTR)hk > 0 && ((UINT_PTR)hk & 3) == HKCR_MASK)

Typically a mask would define all the bits that could be set, and a flag would be the particular bit you want to test. Something like:

#define SPECIAL_HKEY_MASK 3

#define HKCR_FLAG 2

Also, in the following expression:

((UINT_PTR)hk > 0 && ((UINT_PTR)hk & 3)

The second can never be true when the first is false, so you can just drop the first.

These suggestions yield:

#define IS_HKCR(hk) (((UINT_PTR)(hk) & SPECIAL_HKEY_MASK) == HKCR_FLAG)

--Juan