I found this Add-on it's a theme in a way. I am using TB 5 https://addons.mozilla.org/en-US/thu...nity-shredder/
As you can see it takes on the theme you are using in Windows 7.
Here is Thunderbird default with default Window 7 Aero theme
Here it is with default Window 7 Aero theme
Here are some themes I have installed
It has button icons too forgot to show them