Floor_Stop and Ceiling_Stop

[Arctangent]

A rather strange omission, there's seemingly no way to stop a floor or ceiling's current movement with them either being a crusher or ( in the floor's case ) a perpetual platform. It's not hard to see where these could come in handy - overriding the plane's current movement, creating a puzzle where you need to stop the floor at a certain height, allowing an outside source in general to halt a plane's movement, just to name a few.

[Graf Zahl]

added