Hello Sébastien,
I used to have a similar issue on my workstation. All of a sudden, the
Ctrl, Alt and some other modifier keys would stop working. I can't
blame it on Stumpwm though since the same happened under Metacity.
A workaround (rather: an ugly hack) that worked for me was to start a
subshell from ~/.Xsession that would stay in the background and reset
the keymap every 2 minutes:
(while true; do sleep 120; setxkbmap dvorak && xmodmap ~/.xmodmaprc) &
>> I am using VirtualBox quite often
> I had this issue in the past but it was not caused by Stumpwm but by Vmware Workstation.
That's interesting. I used to run VMware Server on the workstation
where I experienced this issue. Seems we have our scapegoat :-)
Un atento saludo
--
Daniel