This function enables the application to query the instance of the Help Manager associated with the application-supplied window handle.

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

HWND    hwndApp;   /*  Handle of the application window. */
HWND    hwndHelp;  /*  Help Manager window handle. */

hwndHelp = WinQueryHelpInstance(hwndApp);