The Back to Close add-on for Firefox adds a simple ergonomic feature to Firefox I am sure a lot of people will enjoy. When you are browsing via the browser or via a tab, if there is no history to go “back” to via the back button – it displays a “close” button instead.
This simple change adds functionality back to the toolbar. The extension also works with mouse gestures and and by configuring the back button on your mouse (if you have one) to the Alt + Left Arrow keyboard combination. Users can also decide whether to show the toolbar icon via the options button in the add-on manager.