>>I meant the situations when the app requires two logins within itself - be it the boss, or a witness. Any of those cases when the user is required to prove having a second person watching or doing stuff or co-signing. I've seen a few of those, and no, it doesn't help to leave the app, switch user, let him launch the app, navigate to the document, do his part, then close the app, logout and let the first user log in, launch the app, navigate to the document, and continue.
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>on the cash register in "semi-kiosk mode" there would be no need to leave the app or (re)launch under new user: after user switch register does a refresh on latest (unwitnessed) data, press button under supervisor account and switch back to normal user. Yes, a few secs more than in app, but nothing earth shattering after first start of supervisor mode.

The app where I saw this was already too big and complicated, and the witnessing was added when it became necessary (law enacted), so there was none of this benefit of knowing the requirements in advance. The advanced was... well, the stage the app was in when this was added :). And it being a big elephant of an app meant that just navigating to the data would be long and cumbersome. Additionally, the requirement was that not-yet-witnessed data can't be saved (probably to prevent someone coming after hours and just „witnessing“ everything that happened during the day), so...

...I'm happy I'm not there anymore. Had any customer read this thread, I'd bet a beer that this check against the AD would become a requirement in a week :).