I had read that guide 3 times - in 2.1, 3.0 and in current 3.1. It describes a process quite good but not the meaning of all that styles.
For now I stuck on themeng TabContainer and ItemList. And it is more about finding what styles are really exist. Following mentioned guide I thought that there was no style for disabled tab - but people tell me to simply add this style to a theme using notepad. And miraculously it works. So I have no idea how to find all styles with their descriptions. And I have no idea why this this area is so bad-documented