[Zope] restrict Add drop-down list in Folder Contents view

[John Hunter]

I have a Folder and I want to restrict the types of objects the
managers of that folder can add to it.  In the Security tab, I can
limit the kinds of objects that can be added, and this works fine, but
the forbidden objects still show up in the drop down list in the
Contents view.

I know I can create a ZClass derived from ObjectManager and just
select the limited set of Subobjects, but this imposes extra overhead
and a proliferation of specialized container ZClasses.  I would really
just like a Folder where the manager sees only the kinds of objects he
has the permission to add in the 'Add' select list.

Any suggestions on how I can do this?

Thanks,
John Hunter
Zope 2.5.x