In Firefox 3.6 and later on Windows you can hide the "Menu Bar" via "View > Toolbars" or via the right-click context menu on a toolbar. Press F10 or press and hold the Alt key down to bring up the "Menu Bar" temporarily. Go to "View > Toolbars" or right-click the "Menu Bar" or press Alt+V T to select which toolbars to show or hide (click on an entry to toggle the state). See also [[Menu bar is missing]] and http://kb.mozillazine.org/Toolbar_customization