The Windows API has the DrawThemeText Function for drawing text to a rectangle in the style of a certain part and state according to the specified Windows theme. (Andreas Rejbrand made a neat application demonstrating parts and states.)
Is it possible to determine what font face, size and colour is used for a given part and state?
GetSystemMetrics can be used to find out about only some system fonts.
There’s a bevy of GetThemeXxxx() functions. You’re probably looking for, respectively, GetThemeFont(), GetThemeMetric() and GetThemeColor(). The metric one was a bit of a guess, there are several other sizing related ones. GetThemeFont also returns the font size. Start here in the MSDN library.