How can I:

- grab keys
- after receiving key event: retrieve information to which window would
it go if no grab would be active
- route this event forward to its original destination (like if no grab
would be active)

In other words: how to attach keyboard "filter"?

I'm starting some interesting project, It's nothing that would harm
people (!), but I dont want to tell more right now..

Mariusz Gniazdowski