I have customized my keyboard layout by changing a line in
/usr/share/X11/xkb/symbols/da (so my onehalf key is now a dollar - easier when coding in PHP).
My problem is that this change is not remembered by Ubuntu when I reboot - the file is not changed, but the key is now onehalf again.
If I go into "Keyboard Layout" in the system settings and then add a random language and remove it again, my own layout is back again.
Is there some sort of cache that I need to update?