code: func ArrowNew(arrowType ArrowType, shadowType ShadowType) (*Arrow, error) {
  	c := C.gtk_arrow_new(C.GtkArrowType(arrowType),
  		C.GtkShadowType(shadowType))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapArrow(obj), nil
  }
docs: // ArrowNew is a wrapper around gtk_arrow_new().