Sorry to make you nervous. Since Fixture is meant to be subclassed, it is of course possible that some people would be affacted by the changes. That is why I only touched the dispatching functionality, which is not something I would expect people to change. (At least I did not need to change anything about the dispatching  when creating my fixtures.) Also, the dispatching functionality was hard to understand, which is one of the reasons I felt the code needed some cleaning up but is also another reason why I would expect people not to have touched it. The fact that Fixture does basically two things is another reason I thought it needed some attention. But I am quite open to suggestions.