This macro expands to:

#define WinCheckButton(hwndDlg, usId, usChkstate)
  ((USHORT)WinSendDlgItemMsg(hwndDlg,
                             usId,
                             BM_SETCHECK,
                             MPFROMSHORT(usChkstate),
                             (MPARAM)NULL))

This call requires the existence of a message queue.