there is no firefox button
I just upgraded to Firefox 4.0. There is no Firefox button for me. I just have the standard windows toolbar menu at top File, Edit, View, etc). I have Windows Vista Home premium.
Alla svar (1)
To get the new interface you need to hide the menu bar. To do that in the View menu select Toolbars, then click on the "Menu Bar" entry.
If you need access to the menus you can press either Alt or F10 to temporarily display them.