I looked at EditArea before building the AppJet Code Editor (ACE). (See our in-browser code editor with syntax highlighting at appjet.com). The problem with E

I looked at EditArea before building the AppJet Code Editor (ACE). (See our in-browser code editor with syntax highlighting at appjet.com). The problem with EditArea is that the overlay method causes visible ghosting when you insert newlines, even on a fast computer. Also not being able to see highlighting on the current line bothered me. I based the ACE implementation on http://marijn.haverbeke.nl/codemirror/story.html http://marijn.haverbeke.nl/codemirror/story.html only simplified the parser and added some features like paren/bracket/brace flashing. The basic idea is to use design mode but keep careful track of the DOM of the design body and cursor. The big challenges then become things like undo support (which we still haven't implemented yet), but the major advantage is that you get a fast and native feel, which is important. We plan to open-source ACE pretty soon.