Thierry de Coulon wrote:

> It does not really explain why I would loose the alt gr key (I would
> understand if I never got it to work). I could also understand if I
> reverted to the US keyboard, but actually all the other key still follow
> the swiss-french setup.

This was a suggestion in conjunction to keyboard and Xorg trying to guess
your hardware. So check first the Xorg.0.log and see what input it
discovers and configures there. 
If necessary try with a custom Xorg config file. You can get the base line
with

       -configure
               When this option is specified, the Xorg server loads all
video driver modules, probes for available hardware, and writes  out  an 
initial
               xorg.conf(5)  file  based on what was detected.  This option
currently has some problems on some platforms, but in most cases it is a
good
               way to bootstrap the configuration process.  This option is
only available when the server is run as root (i.e, with real-uid 0).

regards