This function sets the desktop window state.

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

HWND        hwndDeskTop;    /*  Desktop-window handle. */
PDESKTOP    pDeskTopState;  /*  Desktop-state structure. */
HBITMAP     hbm;            /*  Desktop background bit-map handle loaded or set. */

hbm = WinSetDesktopBkgnd(hwndDeskTop, pDeskTopState);