This example responds to an application defined message (IDM_FILL) and uses WinGetClipPS to obtain and associate a cached presentation space with a window, where the PS is clipped to the children of the window.

#define INCL_WINWINDOWMGR       /* Window Manager Functions     */
#include <os2.h>

HWND    hwnd;           /* PS window                            */
HWND    hwndClip;       /* clipping window                      */
RECTL  rcl;             /* update region                        */
HPS    hps;             /* presentation-space handle            */

case IDM_FILL:
     hps = WinGetClipPS(hwnd,   /* handle of the PS window */
         hwndClip,               /* handle of clipping window */
         PSF_CLIPCHILDREN);      /* clipping flags */
     WinFillRect(hps, &rcl, CLR_WHITE);
     WinReleasePS(hps);