New this build: some usability improvements, and a new audio engine!
A fairly significant addition is you can now add a description (aka comment) to event and instance variables. Thanks to Yann for the suggestion! For event variables these show up in the event sheet to the right of the block:
When choosing a variable you can also see the descriptions:
...and they're also shown in the expressions panel:
This should help make it easier to manage large projects which have a lot of variables, since you can basically keep notes next to the variables.
On top of that, there's a new audio engine and you can now rotate layers! See the changelog for more. We've updated the Space Blaster demo to use the new audio engine, so if you're on Chrome you can try it out.