This method returns a presentation space that can be used for drawing anywhere on the screen.

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

HWND    hwndDeskTop;  /*  Desktop-window handle. */
HPS     hpsScreenPS;  /*  Presentation-space handle. */

hpsScreenPS = WinGetScreenPS(hwndDeskTop);