func (b *Builder) AddFromString(str string) error {
	cstr := C.CString(str)
	defer C.free(unsafe.Pointer(cstr))
	length := (C.gsize)(len(str))
	var err *C.GError = nil
	res := C.gtk_builder_add_from_string(b.native(), (*C.gchar)(cstr), length, &err)
	if res == 0 {
		defer C.g_error_free(err)
		return errors.New(goString(err.message))
	}
	return nil
}
func (b *Builder) AddFromString(str string) error {
	cstr := C.CString(str)
	defer C.free(unsafe.Pointer(cstr))
	length := (C.gsize)(len(str))
	var err *C.GError = nil
	res := C.gtk_builder_add_from_string(b.native(), (*C.gchar)(cstr), length, &err)
	if res == 0 {
		defer C.g_error_free(err)
		return errors.New(goString(err.message))
	}
	return nil
}
// AddFromString is a wrapper around gtk_builder_add_from_string().