inheriting from containers

I've noticed that although I'm allowed to do things like:

  (defclass my-box (v-box)
    ()
    (:metaclass glib:gobject-class))

  (container-add (make-instance 'my-box) some-widget)

I'm not allowed to do:

  (container-add (make-instance 'my-box) some-widget :expand nil)

In fact INIT-CHILD-SLOTS is not able to find the right child container
to instantiate.

Did I totally fail to understand how to inherit from a CLG class?
When I define a new container do I also have to define its children
type? (How?)

-- 
walter pelissero
http://www.pelissero.de

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