This function sets system color values.

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

HWND     hwndDeskTop;  /*  Desktop-window handle. */
ULONG    flOptions;    /*  Options. */
ULONG    ulFormat;     /*  Format of entries in the table, as follows. */
LONG     lStart;       /*  Starting system color index. */
ULONG    ulTablen;     /*  Number of elements. */
PLONG    alTable;      /*  Table. */
BOOL     rc;           /*  Success indicator. */

rc = WinSetSysColors(hwndDeskTop, flOptions,
       ulFormat, lStart, ulTablen, alTable);