When I enable the plugin on trac 0.11. I got error when I click the Management menu. I have this problem with following configuration.
Use Trac 0.11 and use Tracd to run the trac project. The url for trac project would be http://localhost:8000/ProjEnv. The Management menu is pointed to http://localhost:8000/Billing.
After a while I found the cause of this problem. It seems that the code self.env.href return just the server URL. In trac 0.11 they use req.href and it will reture the URL with trac project env. I replace self.env.href with req.href and it works fine.
I am not sure if it is going to break the previous version so I report this as problem to get some respond.