I actually tried to add in that functionality.

I told the modified the program to do this in this exact order.

during lockdown, affected doors would shut themselves.
affected doors would turn off.

Looks good, right? Well the program would do exactly what I told it to do in an instant. The door would begin to shut and then the door would turn off immediately, halting the shut command before the doors began to shut.

The best I could do instead was to set the default not lockdown state to shut doors automatically (any time you opened a door, the door would shut after a delay) to prevent total oxygen loss in the entire ship.

With a little more tweaking to the code, I could also have an extra LCD grouped in the O2 Section with the targeted vent and placed in the adjacent section. These would display something like "warning, room is depressurized! proceed with caution" during lockdown and "room is pressurized" during normal operation.

good news!

okay so I did a little more digging and was able to modify the code so it would detect whether the door was fully closed before disabling the door. I used .OpenRatio == 0 on the doors. In order to turn the door back on, the program would run another check to see if the section is in lockdown first and then it would open the door like in the normal coded behavior.

however

bad news!

there's a reported bug [forum.keenswh.com] that allows disabled doors to "open" and let oxygen pass through even though the animation is a closed door and won't let players through.

Could you show us the piece of code that you changed? I would love to implement it in my ship as well.