Consider disabling AMO search field in add-ons dialog
The Tor developers advise against installing extensions from AMO, due to potential anonymity risks. Unfortunately, end users don't always listen to this advice. It might be a good idea for Tor Browser to consider disabling the AMO search field in the add-ons dialog, which would make it somewhat less easy for users to shoot themselves in the foot. This behavior could be controlled by an about:config pref, so that the few users who actually need to install AMO add-ons can still get the old behavior back. (Making it controlled by a pref would also make it possible to upstream the patch to Firefox.)
A side benefit of this change (not related to anonymity) is that Tor Browser's status in terms of the GNU FSDG is borderline, because AMO contains non-free add-ons. Removing the AMO search field by default would make Tor Browser compliant with the GNU FSDG, which would enable FSF-endorsed distros to distribute Tor Browser.
Because of the relevance to GNU FSDG, GNU IceCat actually already carries a patch for this. See https://git.savannah.gnu.org/cgit/gnuzilla.git/tree/makeicecat?id=6634ee332979f7a78b11cbf09a77364143a981ed#n532 . This might be a good starting point for a proper patch that is controlled by a pref and would therefore be upstreamable to Firefox (thus benefiting both Tor Browser and GNU IceCat).