Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>
>> Let's see what the others think about such a plan. 
>
> Please find attached a patch which gives an impression what that could
> look like. Entirely untested of course, plus for my Emacs, which has a
> different marker implementation, plus I'm not certain which other Lisp
> or C could be affected by such a change.

Had the DEFSYM wrong. With that a simple undo works in emacs -q. YMMV.