Developer reply by Michael J Gruber
Rated 4 out of 5 stars
Please update for TB78 :)
Thanks for the positive feedback.
QC 2.0 used an intermediate API to make it work with TB6x. TB78 dropped that API ("legacy webextension") while the new API ("mailextension") lacks important features (such as content scripts for mail display panes) which will not land before TB82. So for TB78-TB82, we have to use yet another new intermediate API ("experimental API") knowing it might be gone soon, too. I cannot promise for that new rewrite to appear soon, unfortunately.
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