Hello,
     I've added a feature request to add a coffeescript lexer to scintilla here: https://sourceforge.net/tracker/?func=detail&aid=3436256&group_id=2439&atid=352439 and will hopefully start on it when the semester's over (December).  Also, does anyone know:

1) If the lexer needs to be written in c++ (will the lua one Matthew found work?)
2) if it's a bad idea to test this in geany? (I intentionally added the request to scintilla, and can work on it in scite if that's a better idea)
3) if this will cover everything needed for coffeescript in geany once it's done (we'll still need a filetypes.coffee, right? which is just a .conf file that contains the keywords, comment markers, and a few other small things, correct?)

Thanks for any info, and I hope to work on this soon!

Josh