Thierry de Coulon wrote:

> I've got "Enable keyboard layouts" checked, with Swiss and US keyboards
> selected. I've noted I had left the default "104-key", I've changed to 105
> - could that make a change?

yes I have the 105. you could actually play with setxkbmap directly

setxkbmap -model pc105 -layout de -variant nodeadkeys
setxkbmap -model pc105 -layout us
setxkbmap -model pc105 -layout ru -variant phonetic

> 
> AFAIK I have no other xkb option set.

The last tab is about xkb setup and I had some funny behavior.

The last thing that comes to my mind is xorg.conf

Section "InputDevice"
        Identifier  "Keyboard1"
#       Driver      "kbd"
        Driver      "evdev"
        Option      "Protocol" "auto"
        Option      "XkbModel"     "pc105"
        Option      "XkbRules"      "base"
        Option      "XkbLayout"     "us(euro),de(nodeadkeys),bg(phonetic)"
        Option      "XkbVariant"    "qwerty,qwertz,qwerty"
EndSection

then it goes low level usb chipset driver and some kernel options if you
have more exotic kbd. Mine is some of the cheapest 

good luck

regards