The CRSG-extension for default Firefox theme enables combined “Reload-Stop-Go”-buttons old GUI (on urlbar) like it was on Firefox 4-8. It does not create a new button! So if you miss the way you used to have a stop, go and reload button in the address bar – check this add-on out.
Here are a few more features about the add-on from the developers:
Where to find the combined “Reload-Stop-Go”-button?
Rightclick on your toolbars -> customize them -> look for “reload” and “stop” buttons. Order them like in this example:
The button only appears on urlbars right end, when both buttons “reload” and “stop” are placed right after the urlbar like on default non-customized Firefox appearance.
This extension is not compatible with themes and extensions that already style the combined “Reload-Stop-Go”-button.
You can pick up the Classic Reload-Stop-Go Button GUI add-on for Firefox from the Firefox Add-ons website.