title: New way to synchronize preferences for firefox add-on?
body: <p>I maintain a Firefox add-on which stores some settings in a preference <code>extensions.myextension.mypref</code>. In order to synchronize this preference between multiple Firefox profiles, I used to simply set the pref <code>services.sync.prefs.sync.extensions.myextension.mypref</code> to true. This used to work fine until at least half a year ago. But recently, I noticed that this does not seem to work any more. Searching for a solution I found that <a href="https://developer.mozilla.org/en-US/docs/Archive/Mozilla/Firefox_Sync/Syncing_custom_preferences" rel="nofollow">the article that describes syncing of preferences</a> has been moved to the "archive of obsolete content" at MDN.</p>
  
  <p>Is this method for syncing custom preferences of Firefox add-ons no longer supported? And is there any alternative way?</p>