Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Added Lightning calendar support, based on 2.6 non-aero appearance.
Removed blue backgrounds from several dialogs (compose windows, address book sidebar, quick filter bar).
Fixed home screen spacing, and added new icons.
Various other small bugfixes, including borders and close icons.
Removed transparency from the menu bar for better Windows Aero compatibility.
Added the missing chat icons and attachment services.
Fixed issues with tabs in titlebar, tab spacing, and window borders. Made selected messages more visible, and added support for the chat window and app menu.
Thanks to Michal Stanke, whose xpDefault theme was the source for the chat css.
Minor icon updates and additions (the quick search button works again!). Tabs have been cleaned up. Most of the css is now from the TB12 classic Windows skin.
Change the RSS server icon to better match the theme.
Add userChrome.css changes into the theme. Removes the buttons from the message pane, reduces the header spacing slightly, and removes the folder pane header.
To restore the message buttons to the main toolbar, as in TB2, go to Help > Migration Assistant, then select Next > Keep your original Toolbar buttons.