Are you saying to toggle the menu item “View” > “Enter Presentation Mode”? There is no such menu item in Firefox 35, and there hasn’t been for many versions. Th

Are you saying to toggle the menu item “View” > “Enter Presentation Mode”? There is no such menu item in Firefox 35, and there hasn’t been for many versions. There is only “View” > “Enter Full Screen”, which enters full-screen, but with the top bar always showing.