Ever since 9 update I have had white bars at the bottom and top of my browser. Even with using the TBB on non-whonix I still have them. Am I the only one & am I exposed?
Tor Browser in its default mode is starting with a content window rounded to a multiple of 200px x 100px to prevent fingerprinting the screen dimensions. The strategy here is to put all users in a couple of buckets to make it harder to single them out. That worked so far until users started to resize their windows (e.g. by maximizing them or going into fullscreen mode). Tor Browser 9 ships with a fingerprinting defense for those scenarios as well, which is called Letterboxing, a technique developed by Mozilla and presented earlier this year. It works by adding white margins to a browser window so that the window is as close as possible to the desired size while users are still in a couple of screen size buckets that prevent singling them out with the help of screen dimensions.
FYI letterboxing can be disabled by setting
privacy.resistFingerprinting.letterboxing to false in about:config. I don’t recommend this though as it’d worsen your browser fingerprint.
Thank you for the heads up. I kept trying to find the Letterboxing part of the changelog.
This is the long awaited feature that allows users to safely maximize their browser windows without being fingerprinted across sessions.
@Patrick I think the wiki needs to be updated about this as old warnings about changing window size is now obsolete.