[This is preliminary documentation and subject to change.]
Enables a user to set an icon in the image list or to create one if it is not there.
HRESULT ImageListSetIcon(
long * pIcon, // Win32 HICON handle of the icon
long nLoc // Specifies the assigned index
);
If the index specified by nLoc has been used before, ImageListSetIcon replaces the icon stored at nLoc. If it has not been previously used, a new entry in the image list will be added. The icon being inserted must have both the 32x32 and 16x16 pixel sizes defined.