The Flagfox 5.0.0 update has passed Mozilla Add-ons editor review and is now live for updating from previous verisons. All current Flagfox users, including 5.0 beta testers, will now receive an automatic update to the new version at some point. Note that whilst Flagfox 5.0 does not require a Firefox restart to install or update, Flagfox 4.2 requires one to uninstall first.
All 5.0 beta versions have been taken down from Mozilla Add-ons in order to clear the development versions channel to allow beta users to update. (kind of annoying that I have to do this, but Mozilla doesn’t provide another way to manage what updates get sent out to which channel)