Trac Repository Browser bypasses SVN permissions

Hi,

If you have Subversion set up using an Apache server with the 
authz_svn_module providing directory level access control and you set up 
Trac, the Trac browser neatly bypasses the access control.

This is quite a likely scenario as you will no doubt be running Trac on 
the same Apache server as you Subversion install.

It is only a problem if you don't want all your users to be able to read 
the whole repository, but in this case it renders the Trac repository 
browser unusable.  My example is a private company project with nothing 
is visible to unauthenticated users some with r/w and some only read 
privileges.  We also have a contractor who should only be allowed to 
read and write under certain directories on one project.

Is there anyway that Trac could check with the authz_svn_module to see 
if it is OK to browse a particular part of the repository?  Is there a 
library in Subversion for this?

Which level of access does Trac use to read from the subversion 
repository: repository layer, repository access layer or client layer?

Cheers,
Felix