Hi everyone! Here is my status report for February 2024.

As anticipated in my previous report, I have been working on implementing the possibility of setting Mullvad Browser as the default browser on Windows for most of this month. It involved several steps. The first one was to start customizing MOZ_APP_DISPLAYNAME in our browsers to allow installing one build from each channel (stable, alpha, nightly) without conflicts [0]. As a wanted side effect, alpha and nightly app bundles for macOS now contain the channel in their name. The original issue about this [1] was opened in 2018 😄️. The second step was to adapt Firefox's default browser agent. It's a companion exe that helps in various tasks. We disabled it because it isn't compatible with MinGW. Luckily, the compatibility problems affect only some features we are not interested in, so we could disable them and create a reduced agent that is enough for our needs. The final step was to extend the installer to register all the various file associations. I hoped to deal with this step later because it was very involved (lots of Windows registry), but it turned out to be necessary. We're implementing these changes in Mullvad Browser. Only the macOS changes apply also to Tor Browser.

This month, I also took some time to start a different approach to the big rebases we do for our browsers. Traditionally, we stay on Mozilla ESR's channel, and once per year, we skip all the Firefox versions between the two ESRs. I wondered if we could instead spread this work during the year and make more rebases that are smaller and, therefore, potentially easier to review. I've started from Firefox 115 and arrived at Firefox 120. So far, it seems to me that the differences are indeed easier to recognize and explain.

Other tasks I did include the usual monthly rebase and fixing more fingerprinting issues. I also turned off the OS spoofing in HTTP User-Agent in Mullvad Browser [2] and helped a volunteer who's trying to reproduce our builds in F-Droid [3]. Finally, I opened an issue about what we'll need from Arti for Tor Browser [4].

Best, Pier

[0] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42398 [1] https://gitlab.torproject.org/tpo/applications/tor-browser-build/-/issues/40... [2] https://gitlab.torproject.org/tpo/applications/mullvad-browser/-/issues/234 [3] https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/27539 [4] https://gitlab.torproject.org/tpo/core/arti/-/issues/1303