ZDoom

Or by crouching under a fake floor or, presumably, jumping above a fake ceiling.

I can look at the code and see what it'd take to throw in more-aware versions to use, but I'm not making any promises.

The current sector actions don't reliably trigger when teleportation or object spawning is involved, which makes it impossible to run a script on actors that enter the sector via these methods. It would be a bit more useful to have Actor Enters Sector, Actor Leaves Sector, Actor Hits Floor variants that are aware of objects being created in the sector, or being teleported into the sector/already connected to the floor (like by a script).