Glad the debugger is proving useful! We do have lots of improvements planned, such as breakpoints and a 'watch' (so you can make an area with just a few of your own chosen values showing).
@Darklinki - AJAX can work in preview mode if you set up CORS right. Check the manual.
Global variables aren't shown because I forgot about them! Oops, will try to add in the next beta :)
The Steam update was late because I was away for the past two days - it should be live now.