Thanks for the feedback, jojoh. I've posted by replies below.
Very nice and polished.
Thank you

Music keeps clicking on the machine I tested it on. Lots of other things running, so it might be some interference from that (WinXP, java 6, FF 3.5).
Could you elaborate on that? There's also a click sound played when you use a piece - maybe that's the source of the clicking?
One small detail. The yellow balls in the "Next" window were not anti-aliased.
We're using FSAA so it should automatically be anti-aliased. Maybe your video driver doesn't allow software to turn on FSAA? There's also an issue on Mac where we're not able to enable FSAA.
It could be connected with the logs that I saw:
That log message is OK. It's just saying it can't find some resources that are in the full version.