I've not had my Focus too long so I don't yet know all its foibles. Here's one though which I thought I'd ask about.
The other night I switched off the ignition and then switched off the headlamps (they were not on the Auto setting). After I had deadlocked the car I noticed that the dashboard light where, on an automatic, it shows the gear you are in and the mileage etc, and the info display for the radio were still lit but the "interior" lights were not. I waited two or three minutes for these lights to go off but they stayed lit. I checked the owner's manual and couldn't find anything that said this was normal operation. When I went back to the car about 10 minutes after I had locked it, the lights had gone out.
My question to you all is if this is the same on your Focus?