Returns
The return value indicates if the specified function was, in fact,
canceled. If the function was canceled then the return value is WHLLOK
(0). If the outstanding asynchronous function was not cancelled, one
of the following codes will be returned.
- WHLLINVALID
- hAsyncTask is not a valid task handle.
- WHLLALREADY
- The asynchronous task specified by hAsyncTask has already completed.