There's no built-in way to do this, by maybe an add-on could do it. I didn't see anything along those lines -- they are all buttons and menus -- but maybe you'll have better luck: https://addons.mozilla.org/firefox/search/?q=reopen%20closed%20tab&type=extension Also, if you aren't using Chromium much these days, I assume you could re-map that mouse button in case the extension can't take over Ctrl+Shift+T?