I really enjoyed typing along with this 3-part series: https://www.youtube.com/watch?v=oDv6DfQxhtQ Per writes the beginnings of an emacs-inspired Windows (directwrite) text editor.

I want to continue developing it, but have no idea what to do regarding design... I'm considering using Sublime's themes.

Another interesting tutorial: http://www.catch22.net/tuts/neatpad