STR: 1. make sure your Firefox profile is configured to reopen the same tabs after restart (which is the default? IIANM). 2. open a tab with JS (google maps?). 3. open the developer tools, go to settings, and disable js. Notice the option says it's "session-only". The page is now reloaded and no JS executes. 4. Restart the browser (one week later) and be confused why the page is broken - JavaScript will not execute. Open the dev tools, go to settings and you will see the "disable js" checkbox is not checked. More confusion. Now toggle "disable js" twice and the page will load fine (with JS working). True story - this did happen to me and I was confused. We should make sure we re-enable JS in the tab where we disable it, on toolbox destroy. This option should not persist after you close the dev tools, and it should not persist across browser restarts.