how to get a key_press_event for unfocussed windows?

["Karl H. Beckers" <karl h beckers gmx net>]

Hi there,
I have this screencam application and would like to make it 
start/stop/pause recording
at certain keyboard shortcuts. After playing around with mnemonics which 
didn't work
for me because the buttons don't show their text-lables I managed to 
connect a callback
to the key_press_event on the application's top-level window.

Now, that works OK if the application has keyboard focus, but, of 
course, for a screencam
application it probably won't have keyboard focus when I want to stop 
recording (and if I
need to give it keyboard focus with the mouse I can just as well click 
on the stop button).

Is there a way to catch the key press from an unfocused (perhaps even 
iconified) window?
Without the help of the window manager?

All tips and hints appreciated,

Karl.