Here's a quick fix, a new runtime.js for the Mouse plugin:
This won't affect the Arcade since it uses the original r79.3 runtime, but can you give it a quick spin on a Facebook or Kongregate game and see if it helps? Note the app cache might mean you have to refresh twice (check the browser console for app cache activity).
that fix helped for kongregate, so I believe it will also make facebook games work, thanks Ashley you can't imagine my happiness right now :) one thing though, now why use broken runtime on arcade? i understand that it fixes the sticky keys, but i personally believe it's a less of a problem than keyboard not working :)