ok thanks for answering! I only asked cause I did end up green starring every other one of your levels that had a star achievement. thanks for the great levels!

Solution Tip: use the line breaking ability (F) in combination with your line of sight ;)

hey Fergdog... you are right: it is not possible to collect the invisible block in the sky. It is just placed there as a level border (otherwise it would be not possible to build levels with an open sky).
So in this level you can not collect green star achievement. I never intended to make green star achievements in my levels.
But thank you for playing! :)

is there a trick to collecting to invisible white block in the sky? it seems impossible to green star this level