As so many have written before, I really hated when Firefox pulled this native feature. It was innovations like this that had kept me using Firefox as my primary browser. I tried living without the functionality and moving my workflows to what Firefox was a better workflow (pinned tabs, workspaces, etc), but none of them worked nearly as well. I often having several projects going on, with lots of tabs opened related to each project, so being able to intelligently change the context of Firefox to match what I'm working on is a huge productivity boost.

Anyway, thank you for this plugin that brings back this beloved feature!