This function draws a tracking rectangle.

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

HWND          hwnd;          /*  Window handle where tracking is to take place. */
HPS           hps;           /*  Presentation-space handle. */
PTRACKINFO    ptiTrackinfo;  /*  Track information. */
BOOL          rc;            /*  Success indicator. */

rc = WinTrackRect(hwnd, hps, ptiTrackinfo);