I wanted to copy the svorak keyboard map on Linux and exchange the Swedish Å with the German Ü to not need to learn the totally different German Dvorak layout which is nothing like the English nor the Swedish one. But it turns out that to get it to show up in GNOME I seem to need to change a whole bunch of XML files and lst files directly in /usr/share/ where it will be overwritten during the next update. So I gave up on that and will keep using ue, ae, oe the few times I write any German.