menu_handler - specifies the menu handling routines.
May be one of:
XVW_MENUS_XVFORMS - Enable use of xvforms as internal menus
XVW_MENUS_NONE - Disable internal menus
OUTPUT
none
RETURN VALUE
The newly opened display on success, NULL on failure
DESCRIPTION
Opens the display, sets the widget set of choice,
and initializes the xvwidgets library prior to use.
A call to this routine must be made before any other
calls to routines in GUI & Visualization services
are made.