Room A3 "Cloakroom"

The emitter behind the door might be useful.

But the door doesn't stay open long enough for you to be able press the button and get back out. Don't forget to use X or R if you get stuck.

Can you find a way to make the door stay open longer?

Does it still close if there's something in the way?

Open the door, then wedge it with the right-arrow so it can't close. Now fire the right-hand emitter and you're done.