The menu bar is missing when I open Firefox. I went to the Mozilla site to search for a solution. It suggests that you press the full screen button, however that button is not on my browser. So, I added it, and when I tried it I found out that the browser wasn't already in full screen mode. The menu bar may be unchecked on my preferences, but without the menu bar I have no way to get to Firefox preferences...that I know of.... By the way, I'm using a Mac - if that matters.