Rated 3 out of 5 stars

I have used this handy Add-On for several years through several versions of Thunderbird and several releases of this Add-On. Unfortunately though the latest release (4.0.1) does not appear to be functioning properly with Thunderbird 78.5.1 (64-bit). I have lost the arrow to scroll through the various panes. The pull down menu is there to select the folder view , but I think that may be standard in Thunderbird (been so long using Folder Pane View Switcher that I do not know what is standard).. The arrows were the key functionality of this Add-On and I am sad they are no longer there. Hopefully this will be fixed in a future release (or perhaps there is another fix for this?). Yes, I have checked the Options box for "Show Folder Pane Arrows".
EDIT: The Folder arrows do appear when I go to the Add-On through the Add-On manager (under Tools), then click the link to the Add-on, then click +Add to Thunderbird. The arrows are there until I exit Thunderbird. When I restart it, they are gone again.
Issue still exists in Thunderbird v78.6.0 and 78.6.1 (64-bit) and v78.7.1 (64-bit).
This add-on appears to have stopped working all together for Thunderbird v78.9.0 (64 bit).
This extension is somewhat working in v78.11.0 (64-bit) but it still turns off every time I exit Thunderbird and I have to re-add it every time I restart Thunderbird. I leave it open in a Thunderbird tab so I can add it each time.