what has happened to the "Stop Loading" button?
The X or Stop Loading button was very useful to avoid loading ads and stuff I don't want. It seems to have disappeared with the new version.
Alla svar (1)
Firefox 4 and later use a combined Stop/Reload/Go button that is positioned at the right end of the location bar.
During the page load process it shows as a Stop button and after the loading has finished the button is changed to a Reload button.
If you type in the location bar then that button becomes a Go button.
Middle-click the Reload button to duplicate the current tab to a new tab.