winuser.h : remove a fixme and "add" some things

[Dmitry Timoshkov]

"Rémi Assailly" <remi.assailly at free.fr> wrote:

> There were a fixme warning us that a structure were not sure ( line 1898 ).
> I checked it and it seems correct. The only differences I found are :
> - ULONG_PTR dwItemData instead of DWORD dwItemData which is the same
> thing with win32 and also win64 ( according to what I understood )

No, they are not the same. ULONG_PTR is a 64-bit entity in Win64, but
32-bit in Win32.

--
Dmitry.