I can’t claim credit for coming up with this idea, but nobody’s given it a good write-up yet, so here goes.
Step 1: The setup
Create a dynamic lighting section just like you would for a regular door, but don’t use the door tool on it yet
The player view:
Edgar the Sly doesn’t suspect a thing
IMPORTANT Make sure you’re using Standard and not Enhanced dynamic lighting, as that will give the whole game away
Great secret, genius
Step 2: The execution.
If they search for and discover the door, all it takes is a few keypresses (E for edit, D for Door, click and E for edit again) to reveal things