Works as expected, but...: Configured to activate left tab. After closing tab it shows for a moment another tab before activating left tab. Very unpleasant and tires the eyes. If add-on is disabled then activating relevant tab after closing a tab works nice and without such glitches.
The tab that Firefox selects by default may be selected and shown briefly. This is because Firefox 57+ compatible extensions cannot access Firefox's internal working, so the browser's default selection cannot be prevented. This extension can only fix it afterwards.
This is being worked on by a Firefox contributor, and hopefully it will be fixed in Nightly soon.
