Rated 5 out of 5 stars

I used Quickfolders with full satisfaction untill the upgrade to the 78-version stopped this happyness! Any idear, when my happyness will be back? Hopefully pretty soon?can I get a notice on the state to kpfritz@gmx.de?

This review is for a previous version of the add-on (4.18.1). 

I hear you - for instant happiness. you can simply install the prereleae from here:
https://github.com/RealRaven2000/QuickFolders/releases/5.0pre119/
- you need to download the file (do not just click on it because browsers are stupid) with a right-click + save as, then drag the file from your downloads folder - or drag the file link to QuickFolders-wx-5.0pre119.xpi in the assets section below on hte page directly into THUNDERBIRD add-ons manager.
It's pretty much ready for release, I am just working on some marketing to make back the considerable expenses caused by conversion work.