by rsjtdrjgfuzkfg (Developer) on Dec. 26, 2019 · permalink

This add-on is not intended to move Thunderbird to the tray. Doing that from an add-on is no longer realistically possible, so that feature will never be implemented. But there are separate programs that can move any program to the tray whenever you minimize it – this add-on can be used in combination with those programs to get Thunderbird into the tray when closing the window as well.