["... code that's going to be used to make a Vista theme."]

MG The manpage for ttk_vsapi tells you to refer to the Microsoft docs for valid values for classname and partid. They are always somewhat of a nightmare to navigate (and, sadly, regularly move around), but currently you can find the info|%here%|% on MSDN. That page tells you to check Vsstyle.h which I found online easily with the almightly Google.