Safely customizing Tor-browser possible?

is it safe to disable smooth scrolling in the browser

smooth scrolling is fingerprintable - https://dlrobertson.com/examples/scrollinto-view-scrollend.html - but we’re doing something about it - bugzilla 1832598. I haven’t tested to see if this works as intended and there is a follow up bugzilla 1834307

I guess it’s safe enough to watch videos in Tor browser in full-screen these days

full screen/ maximizing will/can “leak” your real screen resolution, even with letterboxing: i.e the letterboxing only steps, so it’s not hard to extrapolate the real size to something expected. Don’t get me wrong, letterboxing is working and makes a difference, it’s just that full screen is a bit different as it’s an upper limit, not some arbitrary user manual resize of the window.

And yes, websites can tell if you’re full screen vs maximized

  • FS I am 2400 x 1400
  • Maximized I am 2400 x 1200 (the toolbar is set as always show), or 2400 x 1300 (toolbar is only set to show on new tab)
  • So even changing toolbar display can affect “user-generated” entropy.
  • even with the above it is not hard to work out I am most likely 2560 wide and therefore 2560 x 1440 - the pioint is not guessing your screen size, it’s the actual reported sizes that are linkable/entropy

If you want to watch videos on a site in full screen, use a new window (or the existing window if no other sites are open in that window), then go ahead - it is only one site and the extra entropy will not be directly linkable. Of course if you use full screen in hundreds of sites, it will start to become a pattern

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