And other tricks. 
How to make a door that will open only after you kick it?
1. create simple swing door 
2. set its wall tile to any DOORTILE# (717 for ex.)
3. Set front and back walls lotag to any free tag,
4. put an activator with the same lotag inside the door sector.
Done.
Now to open this door for the first time you have to kick it!