Good stuff. I could see myself using this. A few bits of feedback:

- Notes should be clamped to screen. There seems to be no limit to how far off screen I can drag something, after which I cannot bring it back (unless I create another note).

- It would be nice if there was some way to snap the notes along a grid so that it's easier to arrange things neatly.

- Collapsible notes would be nice (e.g. collapsing the note so that only the header is visible). Right now each tab has a very limited amount of space.