Eh, Gentoo is pretty quiet most of the time once you’ve got it installed. After that, you just have to keep an eye on it and make sure it doesn’t go off its meds (although once every few years, it will come up with a weird and wonderful way of doing so that you can’t block.)
Automated command-line jobs, in my case, which are technically not random but still annoying, because they don’t need to show a window at all. Interestingly, the one thing I can get to absolutely not pop up any window ever are Perl scripts using Win32::Detached . . . which means that it is possible, but Microsoft doesn’t bother to expose such a facility.