Re: Point of wrong window used in read-from-minibuffer?

[Richard Stallman]

    I don't think the behavior in my above example is consistent
    and predictable: it doesn't happen if the two windows displaying the buffer
    are on different frames, it doesn't happen if current-buffer is displayed
    in one or zero windows on the frame, ...

I am not sure what "it" refers to, there.  What's supposed to be
generally true and consistent is that point in the current buffer
isn't saved and restored by save-window-excursion.  Have you found
a case where that is not so?

    +     /* The code further down is careful to preserve point in current
    +        buffer (if current-buffer is equal to new_current_buffer), but
    +        that ends up moving the window's point if the selected-window
    +        before and after both display current-buffer but aren't the
    +        same window.

I don't think that comment is true.  Since that window was selected,
and becomes selected again, it's point value is not used.
Temporarily, during the body of the save-window-excursion, it is not
selected and its point value is used; but when the
save-window-excursion exits, once again it is selected, so its point
value once again does not matter.  So it can't be correct to day
that its point value gets "moved".

I am not really sure what change your patch is intended to make.