This function returns the desktop object window handle.

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

HWND    hwndDesktop;  /*  Desktop-window handle. */
HWND    hwndObject;   /*  Object-window handle. */

hwndObject = WinQueryObjectWindow(hwndDesktop);