Rated 5 out of 5 stars

by Zverik on Jan. 12, 2015 · permalink

Great add-on, though suffers from some bad management decisions. To restore old tray icon (with left click and message count), open preferences, "advanced→config editor", find "with_appindicator" and set it to false. Then restart Thunderbird.

Source: https://github.com/foudfou/FireTray/issues/147#issuecomment-68603942