I am posting this in context of the new version of Thunderbird. There have been requests for this in thepast, which I presume have gone ignored.
Having a confirm-before-quit option would be very helpful. Other applications have already adopted this some time ago; Mozilla Firefox does it. Particularly, on MacOS, it's easy to fat-finger CMD+Q vs CMD+W (close window).
Is there a good reason why this isn't an option now in Thunderbird or why it hasn't been considered? Is it complicated to implement?