Yep, and they did it well!

Here is a demo if you are interested: http://ajaxorg.github.com/ace/build/editor.html

And here is the GIT repo: https://github.com/ajaxorg/ace

Notice the last commit was only hours ago, so its still quite active

How will this be different?

Yeah, Bespin was trying a similar approach with regards to rendering. They had a lot more baggage (server side code, workarounds for issues that have now been resolved) that is no longer necessary. They've now merged into Ace though and the rendering approach was scrapped in favor of a DOM-based method. I think this gives it a lot more overhead than is necessary.

So are you planning to take the last canvas-based release of Bespin, rip out the crap, and improve from there, or are you going to NIH it?

I'm going to be looking very carefully at Bespin, Ace, CodeMirror and Ymacs. Not sure which, if any, pieces I'll be able to reuse... especially since I'm hoping to move to webGL where appropriate. But I am not going to blindly rewrite pieces that need no such effort.

collect donations, fork bespin... profit