Rated 4 out of 5 stars
I cannot drag&drop mail to any subfolder.
Hope there is autohide disable button or menu. no shortcut-only. ctrl-1 does not work for me, so that I hope there is a button or menu, also.
Dynamically change the key binding is very painful.
Menu item already exists: View -> Layout -> Folder Pane.
I like the idea of a toolbar button.