I can’t really understand in which cases I’d want to use IsAppThemed and when I’d want to use IsThemeActive.
It seems that on Windows 7, both functions return TRUE with Aero or Windows 7 Basic, and both functions return FALSE with Windows Classic.
From what I understand from the documentation so far, IsAppThemed will always return TRUE beginning with Windows 8. That’s about all I can determine – other than that I can’t see how I’d prefer one over the other in any case…
IsThemeActive() tells you whether visual styles are enabled in the operating system. Prior to Win8 you could force that off in Control Panel by selecting the Classic style. Yes, poor name choice.
IsAppThemed() tells you whether the app has enabled visual styles, either by using a manifest or by using ActivateActCtx(), and it wasn’t disabled in the operating system. If IsThemeActive() returns FALSE then IsAppThemed() will always return FALSE.