Check for enclosed space

If I place blocks in a hollow square, how do I make the system check for when the space inside the hollow square is closed off?

Rule: When space inside cluster of objects is closed off, then fill space with black.

I think we will need a better explanation of your problem to be able to help.

Nm. Figured it out. Thanks

— - Could you post how you have done this please ?

Found solution here: scirra.com/forum/building-rooms-with-blocks_topic46361_post495508.html

Thanks