REVIEW ONLY: Animate inline editors open and closed

Finally have a version of this that seems to work. I'm not sure why it took so long to figure this out, since the final version is actually pretty simple, and I could swear that I had a similar version before that didn't work properly. But this seems to do the trick and is straightforward.

/cc @larz0 to adjust the timing if necessary. This feels pretty good to me, but YMMV.