Thanks. It still feels vague though:
[quote:g7ng7pwp]If Is overlapping (or On collision) comes after another condition which has picked certain instances, it can no longer use collision cells.
Does it have to ALWAYS be at the top of an event, or are there exceptions? Does the "picked certain instances" refer only to conditions belonging to the instances in the overlap, or is it conditions picking anything at all (even if the instances weren't included in the overlap)?