Rocks'n'Diamonds

Gravity on. Wind direction up.
Is it accident, that the balloon sometimes gets stuck and
sometimes passes the growing walls?

Good question! I think it's some sort of accident/bug, as I would expect that either the growing wall or the balloon should move first (but then always the same, and not only sometimes).

Apparently this needs some further investigation...

If you move up and the balloon follows you, there's always space of almost one square between them. I think that the space should be blocked. I actually think that all spaces should be blocked between elements moving in the same direction with the same speed. You notice that if you put several equal-directioned butterflies in a line. If they start moving the space between them is blocked. That should be the case at all elements.