WinQueryButtonCheckstate - Remarks

This macro expands to:

#define WinQueryButtonCheckstate(hwndDlg, usId)
  ((USHORT)WinSendDlgItemMsg(hwndDlg,
                             usId,
                             BM_QUERYCHECK,
                             (MPARAM)NULL,
                             (MPARAM)NULL))

This function requires the existence of a message queue.