Computer Learning

[j.c.]

You'd like this one if you aren't using it already:

The tab bar is always showing by default, even with only one tab open in Firefox. You can change this behavior by unticking the 'Always show the tab bar' option under the Tabs section of the Firefox settings.

Tools/Options/Tabs

Now if you only have the one window open your tab bar will go away (assuming you see your address bar, lol... the multiple views/options available in FF can make helping/directing folks a bit of a chore).