WORK
BUT!!!!!!!!!!!!!!

if i paste bunch of urls into textarea(simple html i created) then highlight it and mark visited.....nothing work

This is an update to my original review made on Oct 11, 2017 (I could not find a way to edit it): After using this add-on for a while now, I still find it amazing and works as it should. The only thing I am finding is that every time I start Firefox, my option settings are gone, and I have to reset them. Every time. Hopefully, this will be corrected.