code: func (b *Builder) AddFromResource(path string) error {
  	cstr := C.CString(path)
  	defer C.free(unsafe.Pointer(cstr))
  	var err *C.GError = nil
  	res := C.gtk_builder_add_from_resource(b.native(), (*C.gchar)(cstr), &err)
  	if res == 0 {
  		defer C.g_error_free(err)
  		return errors.New(goString(err.message))
  	}
  	return nil
  }
docs: // AddFromResource is a wrapper around gtk_builder_add_from_resource().