[Zope-CMF] How to list objects of custom type and not of their base type?

[David (Hamish) Harvey]

I'm having trouble getting objects of a custom type to show up in folder 
listings - it goes as follows:

1) I created a new factory based type info, from Document, changing only 
the meta type. Lets call it "Fred".
2) I removed View permission from "Document" for everyone except Manager 
(that's me) in order to stop members from being able to add Documents.
3) I left View permission for Members on the new type info ("Fred") object.

With these settings, it seems that nothing with the meta_type (as distinct, 
I believe, from content_meta_type) Document will show in folder listings. 
People are allowed to create objects of type "Fred", but not see them in 
listings.

Is there any way round this? How can I get objects of type 
content_meta_type "Fred" but not of content_meta_type "Document" to show 
up, where both have meta_type "Document"?

Thanks,
Hamish