*** Please submit non packaging issue (e.g. feature requests) bugs to
the Debian BTS and the upstream bugzilla
(http://bugzilla.mozilla.org/buglist.cgi?product=Firefox) and put a
reference to the bugzilla bug in the Debian bug report, to ease bug
triage for the maintainer. Thank you. ***

Firefox is still in heavy development, and it does not fully support
upgrading from one release to another. Moving your .firefox directory
out of the way should be your first course of action before filing a
bug report. Please see #202130 for an excellent analysis. You may also
want to try removing ~/.firefox/default/*/XUL.mfasl.

Firefox requires the loopback interface (lo) to be up and unfiltered
to accept keyboard input and function correctly. Please make sure this
is the case before filing any bugs.