How do I open the Firefox menu using the keyboard? (I mean the one at the top left corner)
According to bugzilla bug report you cant for now, but they are planning to use alt+f in the future.
Alex Faaborg [:faaborg] (Firefox UX) 2011-10-06 14:12:47 PDT
We are going to use alt-f, it's just slightly more complex since it is overloaded with multile behaviors:
downclick on alt-f: display the firefox menu alt upclick (no f): display the traditional menu bar alt upclick, followed by f downclick: display the file menu in the traditional menu bar