Fun fact 3: in 2020 Logging out of GNOME/KDE/XFCE and others doesn't gracefully shutdown Firefox. It just crashes it so that any time you log out or reboot, the next time you start firefox you will get a warning that your browser crashed and it will attempt to recover the previous session.
Recently, after many, many years, Firefox finally addressed this, not by fixing the problem, but by making the Linux version of Firefox not show a warning message after a crash (it still crashes though). This has the effect of making it impossible to configure Firefox not to remember your tabs. The option is there, but it doesn't work unless you close Firefox before logging out every time. Genius.
This affects both X and Wayland
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