I have noticed that if I add "Greenfoot.start();" to the world constructor (last statement), it works once after compile, but after clicking "Reset" the pause button flashes continuously. This problem does *not* seem to be manifest in the stand-alone build and I haven't tried the pure-java build yet. It also does not seem to be an issue for the previous 2.1.0 Windows build. You can observe this behaviour with the basic wombats scenario by adding the Greenfoot.start() statement in the WombatWorld constructor.