Extremely helpful but it does have some kind of bug when opening secondary email accounts where sometimes it opens in the old simplified gmail version (which is not very practical since most emails nowadays have images on them). I've noticed it only goes back to the normal gmail when i deactivate this extension and it works for a while but it keeps happening. If that could be fixed it would be awesome!

Badge notifications are no longer working for secondary (or more) accounts. Tested on clean Firefox 52.3 ESR install (no other addons, all settings on default).

In terms of general usage, the editor window is too narrow (too much bottom space), with manual resizing possible but not saved (has to be resized for every session)!

A bit slow to load popup content, but still very good.
Any chance to add an option to change a shape of the badge ? There is a circle up here as Logo of the Addon but there is not in the Addon itself.

All is good, very handy. could be a little more responsive.