show registered positions

[Peter Tury]

Hi,

I see in the manual (GNU Emacs 21.3.1 on Win XP; I may switch to using CVS)
that C-x r <SPC> R saves position of point in register R.

Is it possible somehow easily (=using at most a few elisp lines in .emacs?)
to mark those lines (may be: highlight?) what contain saved positions, e.g.
at the left edge of the buffer? Or at least list all registers what contain
a position?

I mean that in the case I have several saved positions, it would be nice to
see them in (pick them from?) a list; or see them when I am around a
"saved" line...

Thanks in advance,
Peter Tury