Problem with an extern Function (MakeLParam)

MAKELPARAM isn't a function, it's a macro.

From WINUSER.H:

#define MAKEWPARAM(l, h)      (WPARAM)MAKELONG(l, h)
#define MAKELPARAM(l, h)      (LPARAM)MAKELONG(l, h)

From WINDEF.H:

#define MAKEWORD(a, b)      ((WORD)(((BYTE)(a)) | ((WORD)((BYTE)(b))) << 8))
#define MAKELONG(a, b)      ((LONG)(((WORD)(a)) | ((DWORD)((WORD)(b))) << 16))
#define LOWORD(l)           ((WORD)(l))
#define HIWORD(l)           ((WORD)(((DWORD)(l) >> 16) & 0xFFFF))
#define LOBYTE(w)           ((BYTE)(w))
#define HIBYTE(w)           ((BYTE)(((WORD)(w) >> 8) & 0xFF))

Neil