Manually editing /etc/X11/xorg.conf and replacing "Driver "kbd"" with "Driver "Keyboard"" worked for me. After rebooting the keyboard layout was "USA", but adding "Switzerland" and removing "USA" was no problem. Here the section of my xorg.conf:
Section "InputDevice" Identifier "Generic Keyboard" Driver "Keyboard" Option "XkbRules" "xorg" Option "XkbModel" "pc105" Option "XkbLayout" "de_CH" EndSection
Manually editing /etc/X11/xorg.conf and replacing "Driver "kbd"" with "Driver "Keyboard"" worked for me. After rebooting the keyboard layout was "USA", but adding "Switzerland" and removing "USA" was no problem. Here the section of my xorg.conf:
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "Keyboard"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "de_CH"
EndSection