There's no possible way to invert a collision because a collision is an instantaneous event, it's called a "trigger"
Instantaneous because it's true just in the tick it happens. Neither before nor after.
Maybe you can understand more about this concept looking at other triggers like "on animation finished", "on key pressed", etc.
They are all triggers.
To recognize a trigger amongst the other kind of condition (normal ones and loops) you can see that they have a green arrow on the left.
You can't invert a trigger.Yann2011-12-01 12:19:59