Rated 4 out of 5 stars
Quite good, but missing a key feature: the ability to choose what views it switches between.
There are seven of them to scroll through(!), including compact versions of some. I wish I could choose to only switch between, say, All Folders and Favorite Folders, without having to scroll through so many others.
Despite that shortcoming this is a terrific add-on, and replaces a function that for whatever reason was removed from Thunderbird.
You can now select which views are active in the pop-up menu and/or arrows. Check out the add-on preferences in the current version of the add-on.