Greetings
My name is Clifford and I use Thunderbird 91.6.1 and i have a suggestion. Years ago there used to be an addon that is no longer available. that placed a row of check-boxes on the left side of the screen beside each message so you could easely check that box, so you could move those messages to a folder(s) or delete said checked messages. It would make it a heck of a lote easer, than holding down the “Ctrl” key. So I suggest that that this feature be included into all
future releases of thunderbird.
Thank you
It is already available as of TB91.
Where would one find it?
It’s the Select Messages column in the Threads Pane.
I hope foxtail63 found it. 
It took a while,And a lot of trial & error, but I found it.
Thank you