Hi, I had some times the problem that for (maybe they tried to hack my VM) some reason
the PS/2 of my old workstation was not usable anymore. The rest just worked, VLC was
playing some shity movie 
But the machine became unusable, as keyboard and mouse were frozen.
If you press the soft-power button the dialog appears (log-off, power down etc). But you can not choose (see above).
So I would like to suggest a feature, where of one presses the soft off button again for less than 1 sec one can rotate the selected option, and press at least 3 sec to “click” on it. So one could safely shut down the machine.
emergency sync by magic keyboard buttons does not work as the keyboard is frozen …
One short press on the power button should always issue a sync command on dom0,
just to be sure, if one is not good at “Morse code” using the soft-power button
Additionally a mgetty at /dev/ttyS0 (NOT /dev/usbtty…)
that connects to dom0 would be good, so one could get a real shell.
But the power button morse feature should be there for all people with stability issues
to be able to shutdown the machine correctly in case of some keyboard/mouse/touchmouse controller issues.
Please look at it. It should be easy to implement, as the code that rises the power off-menue, should just listen to power button pressed events and move / press the selection accordingly.
Thanks for qubes, btw.