Developer reply by Dillinger
Rated 5 out of 5 stars
If you restart Thunderbird, the compact display will be canceled.
I want the option to always be compact.
TB 78.0.1
Add
Thank you for your support.
I can't reproduce this, please use the provided support email address for bug reports.
Edit 3-8-20: it's fixed, waiting for approval.
To create your own collections, you must have a Mozilla Add-ons account.