Hmm, apparently the "gesture" of swiping left should do the same thing as clicking the Back button. I'm not sure how you get a black screen from that. To change what that swipe does, you could try this: (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk. (2) In the search box above the list, type or paste '''swipe''' and pause while the list is filtered (3) Double-click the '''browser.gesture.swipe.left''' preference to display a dialog, change the value to '''cmd_scrollLeft''' and then click OK Does that make any difference for you? I haven't been able to test this because mine doesn't go "Back" in the first place.