IMO, this comes at this at the wrong direction.
Objects should not decide whether they can be added to a given folder, the folder should be the one that makes that decision.
It gives me the heebie geebies to think that every time the add list is rendered, a whole slew of class methods are potentially called to determine what gets put there.
I think (correct me though, if I'm wrong!) that Toby actually implemented the suggestion that Jim made on the comments page of the proposal (add a filter to the meta type info, allowing products to do this without killing performance). We need to find a reasonable place to document the API addition for this before merging it. Brian Lloyd brian@zope.com V.P. Engineering 540.361.1716 Zope Corporation http://www.zope.com