I can't express how happy the discovery has made me that someone has re-established the proper panorama tab group functionality that Mozilla scrapped with the damn Quantum update. The "simple tab groups" add-on is a poor substitute if you've been spoilt with the panorama style.
Photodiode is a bloody legend. They've even gone so far as to improve the stability of the group 'boxes' themselves, allowing you to move and re-organise everything a lot more easily without all your groups automatically resizing themselves like the old inbuilt tab group system worked. My only gripe is that when there are so many tabs in a group that the tab icons have to shrink to all fit, they lose the page title information (showing only the flavicon) and the 'close tab' cross icon, meaning you have to open the tab or resize the group in order to remove tabs. I'd love it if in a future update the cross and title could be retained, no matter how small the tabs have to be shrunk. Even the first few letters of a title are a huge help in identifying what each tab is, and would make this already great add-on even better.