The JavaScript code for it is in https://mozorg.cdn.mozilla.net/media/js/firefox_tour_whatsnew-min.js https://mozorg.cdn.mozilla.net/media/js/firefox_tour_whats

The JavaScript code for it is in https://mozorg.cdn.mozilla.net/media/js/firefox_tour_whatsnew-min.js https://mozorg.cdn.mozilla.net/media/js/firefox_tour_whatsne... It uses the following command to open the menu: document.dispatchEvent(new CustomEvent("mozUITour", {bubbles: true, detail: {action: "showMenu", data: {name: "appMenu"} }})) I found the source code here : https://github.com/Unfocused/mozilla-uitour/blob/master/src/mozilla-uitour.js https://github.com/Unfocused/mozilla-uitour/blob/master/src/... This code http://dxr.mozilla.org/mozilla-central/source/browser/modules/UITour.jsm http://dxr.mozilla.org/mozilla-central/source/browser/module... seems to handle to JavaScript event dispatches.