I know that Firefox has a Letterboxing feature to prevent window size-based fingerprinting, but I would like to know if situations like playing a video in fullscreen mode bypass the Letterboxing protection and compromise privacy.
What is the compromise you think it may cause?
I think it’s asking if the letterboxing feature gets disabled if media it’s fullscreen and break window size-based anti-fingerprinting.
According to the article I linked above:
Firefox’s letterboxing support doesn’t only work when resizing a browser window but also works when users are maximizing the browser window, or entering in fullscreen mode.
They stay on when using the browser in full screen mode. I don’t remember if they’re disabled when watching full screen media, but even if it is bypassed it is not a huge privacy concern (unless you have a super weirdly unique monitor). Letterboxing is meant to make unique browser window sizes less identifiable, because you could easily resize the window to a random rectangle size nobody else is using. You can’t do that in full screen anyways.
If you’re watching a full screen video you’re blending in with everyone else watching a full screen video, which is plenty of people.
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