Hi Federico,
Hmm. This is becoming somewhat problematical. Fedora is clearly significantly different to Ubuntu, in relation to the behaviour of GNOME. At this rate, there will need to be a section for every major distro of Linux, due to variations. It will be infeasible to make this generic. I also run Debian and it has its differences also. I suppose this is the nature of Linux distros.
The Lilypond Usage section is in fact incorrect regarding Apparmor on Ubuntu and should be corrected, as this is one of the most difficult part, that few people understand. Not many users customise Apparmor - it's quite arcane.
While I am happy to learn the development submission process, it's true that this page is somewhat more tutorial than reference. That's in fact the idea. So now I am favouring a blog post at Scores of Beauty. But I will reflect on it.
I run virtual Linux machines and I am happy to run up all the major distros and to account for all the differences, but this seems like a large amount of work for something that people don't necessarily even want anyway. And there is no way I am going to write anything for Windows, or Mac.
Andrew