At first I used two squares together and just selected some line. I textured it as a door, and then i set the special to door.
Later i used a little tunnel where i set both sides to door.
I've been trying to make doors, I tried in slade 3 and UDB, but they never work right.
Either they
Do Absolutely Nothing
Sink into the ground along with the walls of the next room
Lower the celing of the room
if anyone can help that would be great