This function queries whether a point lies within a rectangle.

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

HAB        hab;   /*  Anchor-block handle. */
PRECTL     prcl;  /*  Rectangle to be queried. */
PPOINTL    pptl;  /*  Point to be queried. */
BOOL       rc;    /*  Success indicator. */

rc = WinPtInRect(hab, prcl, pptl);