q2drhovgqw1--- via Tails-testers:
>Previousley withTails 6.18 
><https://tails.net/news/version_6.18/index.en.html> and earlier, Tor 
>would not open to full screen, in the Test 7.0-rc1, Tor opens to the 
>screen full width. I seem to remember this was to do with letterboxing 
>etc,
Hello, thanks for your test. That's the same behavior I see in 6.18... 
and this is fine :)
Indeed, Tor Browser does the so-called letterboxing, which is an 
effective fix for fingerprinting attacks based on screen size. Exactly 
because letterboxing is in place, Tor Browser can be safely opened full 
size (and actually, at most sizes).
bye,
-- 
boyska