I've been looking for an addon to do this for a long time. It works as I want it to.

I realize that the instructions said it needs Tree Style Tabs, but I did not realize that that meant the custom tab colors would only show up in the Tree Style Tab list and not across the main tab bar itself. Perhaps this point could be clarified in the instructions?

Anyway, once I realized where the colors showed up, I was happy to have access to options I'd wanted to have for a long time. Well done to the developer, emvaized!