magit does similar things with interactive rebases, although it is keyboard driven (I never tried to use the mouse). Another nice feature is the instant fixup where you can easily commit+rebase+fixup (think of commit --amend, but against any commit).

FYI, command-line Git is where fixup and autosquash come from:

https://blog.sebastian-daschner.com/entries/git-commit-fixup...

Magit makes the feature easier to use and more discoverable, though.

yes of course, the magit rebase buffer is literally the git rebase file with a custom emacs mode on top for interactivity.