I've seen that before.
We once had a boom with a game called "Moorhuhnjagd", which was about shooting down grouses and looked like
this.
The tricky stuff is that game had such a cloak device implemented, which opened a fake notepad with random stuff written on it.
So all the businessmen could play it in their offices without getting in trouble.
And this is completely off-topic, I'm sorry.
To come back to the topic:
I usually don't have anyone who could walk in on me right now, but back in the days I always had an empty browser open and if some shit would happen I just had to Alt+Tab and everything's fine, since I don't watch my porn with audio (hate that fake moaning).