[Zope] Problem with tree and Navigation product revisited

[Carlos Henrique Bauer]

Hi,

I'm trying to use the Navigation product in a tree but I got a problem. The
file and document are being rendered as folders which contents are the contents
of its parent folders. The tree is defined by the following dtml statement:

<dtml-tree branches_expr="navigate_filter('private', 'no', ['Folder','File', 'DTML Document'], 1)"
 sort=title
 skip_unauthorized=1
>

Due to some obscure reason, the call to objectValues method in the
navigate_filter function is not returning an empty list for non folder objects.

I managed to workaround that problem by adding the code of navigate filter to
the ObjectManager class. I add another method with the same name to the class
SimpleItem but which returns (). If I don't add that method to SimpleItem I get
the behaviour described above.

Questions:

1) Is it a feature or a bug of Navigation produtc?

2) There isn't a more elegant way to solve the problem?

By the way, I'm using Zope 2.0.1. 

Best regards,
-- 
Carlos Henrique Bauer