Many, many thanks, you're right, and I have got it work now !

https://github.com/Folcogh/FMetro/blob/master/NativeEventFilter.hpp
See this class : https://github.com/Folcogh/FMetro/blob/master/NativeEventFilter.cpp
(like you said, I should add a call to UnregisterHotKey in the dtor)

I have removed the type check, and I have read the sources of Qxt : http://libqxt.bitbucket.org/doc/

The documentation says something about returning 'true' after reading the event, but Qxt doen't act like that.
So the Qt's documentation seems rather wrong about global hotkeys.

Also don't forget to change the second param (the id) of the RegisterHotKeyif you're gonna use several different hotkeys.

Qxt uses the key code to identify the keys, it's a nice idea.

Now I have to work learn how Windows maps the keyboard, and how Qt does it, to allow me to translate a Windows key into a Qt key.

Many thanks again, it was a must-have feature to my program. :)