Might be nicer if you changed it to work with Greenfoot actors rather than swing dialogs? There's a new constructor on GreenfootImage in 2.0.1 that should make this easy, and it saves dialogs popping up all over the place (sometimes they appear on a completely different monitor for me!)

Sometimes it really is impossible to beat - for one level I ended up right on top of an enemy before hitting the "run" button so there really was nothing I could do! Perhaps put a check in to avoid that kind of situation? Or reset the character's position each time to a known "safe point"? :-)

I got to level 5 by just leaving the ball in the bottom left corner - nice start though! Perhaps work on some of the collision response code, it'd be cool if the balls bounced off each other realistically rather than just in a straight line (and sometimes two balls get stuck vibrating together instead of breaking apart when they collide.)

I can't seem to get a positive score on this - just the negative number of clicks that I made? In terms of the swing components, they're far better not used on Greenfoot scenarios - it's much nicer to have everything you need in the actual scenario rather than have dialogs pop up all over the screen (on my setup for instance it appears at the top left of my left monitor, which is some way away from the scenraio which is on the right hand monitor!)