官网介绍:
https://flagfox.net/viewtopic.php?t=552Flagfox 5.2.3 was the last standard version of Flagfox to support
versions of Firefox prior to Firefox 57, due to a mandatory rewrite to
use Mozilla/Google's new WebExtension API, after which point Mozilla
banned all prior "legacy" APIs and banned addons that used them from
posting any updates, as of the Firefox 57 release. Everyone should use
Flagfox 6.0+ if it is supported by your browser version. Flagfox 5.2.x
is currently the only version of Flagfox to support Firefox 52 ESR or
SeaMonkey (which is currently based on 52 ESR), as WebExtension support
is insufficient in those versions. Firefox 52 ESR will receive
security/stability updates until mid-2018, after which point you'll need
to upgrade or be unsafe, regardless of whether you like their new
versions or not. Flagfox 5.2.4 and potential future updates exist to
continue support for Firefox 52 ESR, which Mozilla doesn't really fully
support, but is still in wide use. Updates will not be released every
month and will not be released indefinitely.
Use of particularly old versions of Flagfox
will eventually result in inaccurate flags, as your IP location database
will be out of date.