Patch Set 2: I would prefer that you didn't submit this

I'm not sure what this does, or is supposed to do. This git history page flashes and the selected revision changes, but nothing visible happens. 

Looking at the code makes me scratch my head. Seems the class is some legacy from the time when I did not know much at all about Eclipse...

I think we should bring up a compare dialog. The old history page actually had some logic like that as an indirect action, but the current version doesn't.