I installed Editarea and liked it a lot, although from the start it had a problem:
I'm using a TwentyEleven child theme, and I haven't really added much content yet. I'm just setting up the styling.
Editarea worked fine with the child theme css, but when I would view the parent theme css (to copy sections) I would get a script error popup about Editarea. (That little popup that says a script has stopped working, and you have a choice of what to do about it.) It didn't really matter to me, since I was only copying bits of the parent theme, so I just clicked "NO".
Anyway, I changed over at some point to a brand new Child Theme. Very bare bones, not much different from the parent theme. I noticed that Editarea had gone away. The toggle box was gone. I tried checking Editarea's settings but they were still the same. I tried deactivating and reactivating it. Still nothing. Then I deleted and reinstalled it. Still nothing.
Sigh. My site is here. It was only a nice little convenience, not a necessity, but I really had gotten fond of it before it vanished.