Alright.. that was quicker than I thought. The below should be a solution to your problem, which we'll test further and likely include in all future releases:
/components/com_jfbconnect/controller.php, line ~117, change the line from
print 'window.top.location = "'.$permsUrl.'";';
TO:
print 'self.location = "'.$permsUrl.'";';
window.top will redirect the entire 'window', while self will redirect the frame.. which in most sites that don't use frame, will be the entire window.
Please test, if you don't mind making the code change, and let us know how this goes. Thanks!