Re: customize-face: inverse-video does not work when customizing the menu face

[Richard Stallman]

    If by ``invariable'' you mean that Emacs cannot change them, then this is 
    not true: we do change them by putting resources into the xrdb database.

By the ultimate defaults, I mean the ones that would be used when the
user and the application do not specify any colors.  Emacs can override
these but it cannot change them.

    If you mean that the ultimate defaults are constant and thus known in 
    advance, then I guess that's true, but I don't know where to get the 
    values of those defaults.

You could start Emacs without any specifications for these colors
and see what you get.  If the ultimate defaults are invariable,
this will show you what they are.