Hot answers tagged firefox
If you have SQLite you can run this command: echo 'DELETE FROM moz_historyvisits WHERE visit_date < strftime("%s", "now", "-5 month") * 1000000; VACUUM;' | sqlite3 places.sqlite
Setting the preference "browser.helperApps.neverAsk.saveToDisk" to "application/octet-stream" appears to give the desired behavior for unknown MIME types: http://forums.mozillazine.org/viewtopic.php?f=38&t=2430485 For known MIME types, use random♦'s solution above. These two approaches combined should give you the behavior you're looking for.
After reading some pieces of the Firefox source code related to the preference and a Bugzilla ticket that's related to it, I've come to the conclusion that the preference works serves as a kind of "trigger" when the fonts installed on a computer change. Web pages can specify what font should be used for (parts of) a web page, and to which font a browser ...
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