Oh yes, that. I noticed that that is more effective when the floor is black/white, and it's better to use dark versions of blue for blue floors, red for red, etc.
Thank you sooo much my maps are now fixed as i just added a blank script to them.i just selected as many blockers as had to and one blank script fixed everything.my rock'n' roll Map , blockers held rocks in air to fall when shooting scripted barrells.it works again.your a ledgend.