This example uses the WinQuerySysColor to find the RGB index of the system push button, SYSCLR_BUTTONDEFAULT.

#define INCL_WINSYS
#define INCL_WINDESKTOP
#include <OS2.H>

HAB  hab;
LONG lRgbColor;

lRgbColor = WinQuerySysColor(HWND_DESKTOP,
                             SYSCLR_BUTTONDEFAULT,
                             0L);