The new Ubuntu 11.04 Natty Narwhal uses a Global Menu which puts the applications menus (File, Edit ,View…) on the top panel. In Firefox, this also removes the Firefox menu button in the upper left corner of the browser window. If you liked that menu button and would like to get it back then you are lucky because it can be done in just 2 easy steps!
First Step: Open the add-ons manager by going to “Tools > Add-ons” or you can press the shortcut keys “Ctrl + Shift + A”
Second Step: Locate the add-on “Global Menu Bar Integration”, disable it by clicking on “Disable” then click on the “Restart” buttons that will appear next.
Third Step: In the top most of the Firefox window itself, click “Views > Toolbars” and uncheck the “Menu Bar” option.
TaDa!! The Firefox Menu button is back in it’s place.