CTRL+Q should only close the current window, not all windows.
-1 from my side.
Ctrl-Q is standard shortcut for exit application. If one wants to close a window, use Alt-F4 or (x) button in upper right. The hole behaviour of a multi-mainwindow app versus several single main window apps is unfortunately not properly definded. But IMHO this should be reassiged to the HIG Group before every multi-mainwindow application implements it's own behaviour.
Just my 2 cents.
The Ctrl-Q use case is: I use 'start falcon with the the windows and tabs as on close' . This implies I need a way to close all windows at once. Otherwise flacon will not (re)start with several windows.
After along thinking I believe this is exact example of what should be handled by Keyboard Shortcut Manager and not directly in the code.
So, instead of trying to go around all possible situations when this shortcut should or should not be active, we should work on implementing Keyboard Shortcut Manager.
Since this is the case, are there any volunteers ?