This function sets a presentation parameter for a window.

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

HWND     hwnd;            /*  Window handle. */
ULONG    idAttrType;      /*  Type of presentation parameter attribute to be set. */
ULONG    cbAttrValueLen;  /*  Size of the buffer pointed to by the pAttrValue parameter. */
PVOID    pAttrValue;      /*  Pointer to the presentation parameter's data. */
BOOL     rc;              /*  Success indicator. */

rc = WinSetPresParam(hwnd, idAttrType, cbAttrValueLen,
       pAttrValue);