I was playing with mikoportals, and i tried to close the portal sector as a door, and i saw that the sector ceiling lowers infinitely. And i thinked: Why not use this as a vertical scrolling wall?
Obviously, it haves some limitations:
Doesnt work on GZDoom, like normal mikoportals
In some time the door stop renderizing, but if it haves 1 sided no-unpegged linedefs these still scrolling.
You have to make impassable all the passable linedefs of the "door", because