Nautipolis for Thunderbird: High-quality, solid theme based on icons from art.gnome.org. Fully compatible with from 5.0 upto latest nightly build (currently 27.0a1). Full support for Lightning/calendar.
Default XP theme for ThunderBird 45. (Mail and Lightning calendar) --- After long time of inactivity, Michal Stanke decided not to update xpDefault. I propose to try, and make this version, tested on Vista and Win 8.1. new 45.0.3 16 oct 2016
MicroThunderbird, for Thunderbird. Based on LittleBird, sporting the same screensaving, and with same 'retro' design (8-bit colors). Fully compatible with from 5.0 upto current nightlies. Full support for Lightning/calendar.