This overlaps with the existing version tree functionality in Plastic, and with the existing annotations functionality - and is probably related to method history too.

My use cases are:-

1. I see a piece of code that is broken, but don't know anything about what that code did in the first place, when it was introduced or who did it, and what were the checkin comments.

2. Again, I see a piece of code that is broken, and I want to jump straight to the diff for that piece of code in whatever revision introduced the breakage. If that revision turns out not to be the one that broke that code, I want to jump back further without seeing other revisions that had nothing to do with that section of code.

What I'm looking for is some way of focussing on a specific section of code and going back over revisions to see how that section of code changed, and ultimately how it got in the first place.

For added value, I'd like to track that section of code as it moves around a file or across files.

I've see annotation GUIs in other VCS offerings that allow a progressive jump back by line - this addresses my use cases for 80% of the time.

Occasionally I'd like to track code motion too - so maybe some method history using the Semantic Outline mechanism would be good?

Alternatively, could there be an option in the file 2-d history view to lock on to a line in the preview pane - that would be awesome, and I think that if Semantic Outline is enabled with analyse refactors, it would cope with code motion too.