a for effort. Given this was last updated june 2019 and I'm writing august 2020, the suggestions won't matter much. UI is... ugly. At least put some Arial instead of Times new roman. Plus there's a lot of wasted space between the entries aka the line height is too big.
What I don't understand with most sorting addons, they all use last access date and not date opened. This addon does it too.
The sorting cannot be carried over to the actual tab it seems.
Other than that not much to complain about.
addon/clicktabsort/ seems to be a usable alternative

Awesome!!!

It sorts Tabs in the popup window but does NOT rearrange tabs in the browser in the sorted order. Pretty much worthless...