Feature request: "show diffs" on edit drafts

Are you talking about edits or new replies?

I would really love to easily find out the difference between the edit I started some time ago and the post as it is publicly available at the moment. However, I would like to see it when I continue editing and not after I have edited.

For new replies, the edit would not make much sense to me, because thanks to autosave, there is no difference, is there?