[Vala] Struct property bug: get, but not set

[Nor Jaidi Tuah <norjaidi tuah ubd edu bn>]

The following displays 0 for button.color.red.
Expected: 100.

        void main (string[] args) {
                Gtk.init (ref args);
                var button = new Gtk.ColorButton ();
                button.color.red = 100; /*1*/
                debug ("%d", button.color.red);
        }

Line /*1*/ is compiled to:
        gtk_color_button_get_color (button, &_tmp1_);
        _tmp1_.red = (guint16) 100;

There is no set access to button.color at all!

Is this a known bug?

hand
Nor Jaidi Tuah