This function cancels a request for an application to shut down.

#define INCL_WINMESSAGEMGR /* Or use INCL_WIN, INCL_PM, Also in COMMON section */
#include <os2.h>

HMQ     hmq;            /*  Handle of message queue for current thread. */
BOOL    fCancelAlways;  /*  Cancellation control. */
BOOL    rc;             /*  Success indicator. */

rc = WinCancelShutdown(hmq, fCancelAlways);