[PyGObject] access to systems color palette

[<c buhtz posteo jp>]

Is there a way to read the systems colors?

MS Windows and all GNU/Linux window managers can customize there
appearance: fonts, fore-/background colors, etc

I want to ask (a most platform independent way) the system what is
your highlight color? e.g. when a menu entry is marked

Can I access informations like this somewhere?