Re: inactive-mode-line face?

[Richard Stallman]

    Well, one problem is that all the windows become inactive when you are
    in the minibuffer.  That is, as soon as you type "M-x" or "C-x C-f",
    all the mode lines become displayed in the inactive face.  This might
    be regarded as a feature, but perhaps users would like to know what
    window is active even when they are typing at the minibuffer prompt.

I think that when the minibuffer is selected,
the window in minibuffer-scroll-window should count
as the "selected" window as regards the mode line.

(That is the window that was selected "outside" the minibuffer.)

    Also, I wonder whether the default for this face should really be
    different from the mode-line face.  Perhaps we want that by default
    this feature is invisible;

This feature should be good for beginners if we get the colors right.
So the default should be that it does something you can see.