This function sets the pointer position.

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

HWND    hwndDeskTop;  /*  Desktop-window handle. */
LONG    lx;           /*  x-position of pointer in screen coordinates. */
LONG    ly;           /*  y-position of pointer in screen coordinates. */
BOOL    rc;           /*  Pointer position updated indicator. */

rc = WinSetPointerPos(hwndDeskTop, lx, ly);