I'm putting together a little overview/"cheatsheet" file of the theme capabilities in ST3.
WIP but still practical to have while making a theme even at it's current state so here is a link.
Link to Gist
Will eventually map it all out and continue to test for unknown class, property and attribute combinations and so on.
If you know of any combinations not in the default theme I'll be happy to test to confirm and add it to the overview.
(And any other tips/tricks for that matter)