How to use G_CONST_RETURN?

Hi,

I tried to use G_CONST_RETURN for the type of return value,
but an error occured.
  loqui-style-entry.gob:85: Error: syntax error before '*'

The code is here:
        public G_CONST_RETURN gchar *get_string(self) {
                return self->color_string;
        }

G_CONST_RETURN is useful to clarify that the value need not be freed.

-- 
Yoichi Imai <yoichi_at_silver-forest.com>