I am trying to use a func_door as a column which will slide down from the ceiling. I had been using a func_movelinear before but it creates a problem in that you can stick portals to it once it has stopped (as mine does). I have also been making non-portable surfaces into doors (to achieve the non-portable effect), and that's worked great, so i think this would make sense. however, i can't get this door to move at all. is there something i have to do, manually identifying the door frame, or something? the only variable relating do distance is the lip, which references the frame...

Make sure you don't have the Start Disabled flag checked, and that you have the proper Outputs going to it.

haha, i figured it out. kind of a weird way of doing it, had to give it a negative lip.

That's pretty common actually.