code: func BoxNew(orientation Orientation, spacing int) (*Box, error) {
  	c := C.gtk_box_new(C.GtkOrientation(orientation), C.gint(spacing))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapBox(obj), nil
  }
docs: // BoxNew() is a wrapper around gtk_box_new().