[Zope] Creates classes available to container but NOT add products menu

[chrisf]

RegisterClass is cool

But what if you don't want to register your product.
When you create a product and add a ZobjectManager derived Zclass, all
subsequent subclasses appear in the subobject menu but not the Products
menu.
I have a heap of classes. I do not want every class in the add Products
menu.
I do want them to be available to the top level container class.
How do I do this from within python product code.


Chris