Hmmm, I discovered that I can open tabs within the browser within a browser. But, as you said, I see no real use for this. It just takes up more space at the top of your screen.
Edit: other observations:
This can be done in layers, or multiple levels; in other words, a browser within a browser within a browser, etc. The home page in any of these browser windows created by opening a browser within a browser is the Mozilla Firefox Start Page. And, switching between tabs in a sub-level browser window does not change the URL shown in the web address box.
Interesting but worthless.
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