An HTML editor for ChordPro songs.
You can experiment it on http://oliverpool.github.io/chordpro-editor/.
The concept is simple: a div is added behind the textarea and backgrounds are added where needed.
This approach prevents complicated contenteditable tweaks (especially when dealing with shortcuts and markup).
Except the "header information" (like title), it support most of the ChordPro song features (at least the one used by patanet project).
It uses the awesome PEG.js library.