Since Firefox 57 there is no way to disable Ctrl+Q shortcut by plugin on Linux (see this bug). All workarounds I've found are based on setting the global Ctrl+Q shortcut to "steal" it from Firefox. But this will disable this shortcut in every application, and I want to disable this shortcut only in Firefox, without affecting any other app.
Is there a way to disable or catch shortcut only for one application? I'm using Ubuntu with Unity.