It does do `diff`, once you select the revision you want to "diff" with. To the old behavior, you would press ENTER when the second panel is shown (effectively selecting the HEAD). What is there so bad about this? Is it because it's a bit slower? I guess if that is the case it could be put in a separate `diff` command, but being able to "diff" your work against different revisions is very useful at times, and I honestly wouldn't say having the command do a superset of what it did is a "major regression".