This is cool, a nice beginner or general convenience feature might be the ability to highlight some basic scales like major/minor. This would probably get people off the ground writing music that sounds good much quicker.
it "works" in firefox, but the playback is laggy and weirdly timed. very cool tho!
The latency is horrendous, I use a real-time kernel to make music @3ms< you're never going to get that with a fully streaming application however, you could possibly send bigger chunks of data which interact on the client-side. It's still problematic, but bravo! Valiant effort.