Forgive me for intruding into the realm of code-monkey-business here, but for the love of God, please do not use the - and + metaphor for expanding and collapsing things. It's one of those idiotic things that persist in Windows, as well as (God help us) being copied in other GUIs, despite the fact that it makes no logical sense at all...

Other than that, it looks interesting so far. Let's see how it develops.