Hi,

The initialization of ediff control window is affected by the fullscreen in
window-system-default-frame-alist.

If I put in my .emacs:
(cl-pushnew '(w32 (font . "Consolas-14")
                  (fullscreen . maximized))
            window-system-default-frame-alist)
So that for each new frame, it will try to make the frame fullscreen
including the edif control window. And when the ediff control pop-up on the
right-side of the screening from top to bottom (like fullscreen). When I
type "?", it shows the help message windon. I type "?" again, it gets back
to the control windown, and now the window is on the top-right of the
screen as a small window.

I was suggested by *Stefan Monnier:*

    (with-eval-after-load 'ediff-wind
      (push '(fullscreen . nil) ediff-control-frame-parameters))

It solves the problem.

I think the default behavior of the initialized ediff control window should
not be full-screened. I suggest to add '(fullscreen . nil)  to
ediff-control-frame-parameters as default.



Best Regards,
Shuguang Sun