[plt-scheme] adding children

How do controlls normally register with their parent?  they don't seem
to call add-child in the parent.  for example, i tried inheriting from
a panel, then overriding add-child.

(override*     
   (add-child
      (lambda (decoy ...) (display "intercepted add!"))))


if i call (send new-object add-child) it works, but if i do
(new message% (label "stuff") (parent new-object))

then it automatically adds to the inherited vertical-panel, without
ever calling add-child.  (I'm trying to intercept the add request, and
get the requested object to add to a panel thats a child of the
inherited vertical-panel)

Corey