It is a Theme of the Mac Leopard-style which did iLeopard in a model.
MagicSLR extends functions and buttons to get and send messages. Many users missed a combined "Get/Send" button in Thunderbird. MagicSLR provides this button and more.
This theme is the skin which can change your Thunderbird like LeopardMail.
All-in-one Mac style theme! Please check preview here first (it rocks):
To get sub themes: Open Add-ons window, right click on Cutebird, click "About Cutebird"
more info at http://foxdie.us