I think it would be good to have several tab variants/styles. For reference, the current tab design is:

A few alternatives could be:
Miniature-left:

Miniature-middle:

Another idea is hover prompts... excuse the horrible edit.

I think having the active tab blend in with the window would be nice as well

Fixed rendering in 3.0.56, native tooltip support with overrides for now; will add setters soon.

It's only been four months, but I've finally gotten around to miniature icons.