MMIOM_SETIMAGE - Description
This message is sent to an image IOProc to select a new image index in the
image file.
pmmioinfo (PMMIOINFO)
usMsg (USHORT)
ulParam1 (ULONG)
A
ULONG containing the new image index. If the index is less than the count,
then an existing image will be addressed. If the index is equal to the count,
then a new image will be created when mmioSetHeader
is called. Indexes greater than the count will generate an error.
lParam2 (LONG)
This
parameter is not used.
rc (ULONG)