WinWakeThread wakes a thread that is waiting for input, so that a DosPtrace STOP command can be processed.

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

HMQ     hmq;      /*  Message-queue handle of the thread to be scheduled. */
BOOL    Success;  /*  Success indicator. */

Success = WinWakeThread(hmq);