This function sets the current clipboard-owner window.

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

HAB     hab;   /*  Anchor-block handle. */
HWND    hwnd;  /*  Window handle of the new clipboard owner. */
BOOL    rc;    /*  Success indicator. */

rc = WinSetClipbrdOwner(hab, hwnd);