Basically I want a text editor that is:
- Simple in visual design and uncluttered (like Byword)
- Powerful and extensible like emacs (with hooks, etc, so I can customize it to my needs). When I say "extensible", I mean the more the better. I don't have a particular hook/extension in mind, but basically the closer to emacs the better. (I think of emacs as being the pinnacle of extensibility.)
I know there's Aquamacs (which meets 2), but Aquamacs looks really ugly and not at all appealing (so doesn't meet 1).
Please make answers detailed! Explain why the text editor you are recommending fits this question. In what ways is it extensible? What nice UI touches does it have?
The goal here isn't to build a list of text editors; it's to compile information about exactly how various text editors are both well-designed and extensible.



