How to highlight the right-margin column?

[Eric Pement]

Using GNU Emacs 21.2.1 on Win2K system:

I would like to have, in text mode, an option to toggle the display
of the right margin line. In particular, I'd like to be able to
toggle the background color of the current fill-column to display
a vertical stripe in my editing window, thus showing where the text
is in proportion to the right margin (fill-column) setting.

Has this been done before, and if so, can anyone point me to how
to do it?  I've checked M-x apropos, both FAQs, EmacsWIKI, and the
google archives of this newsgroup, and haven't found the answer
yet. Thanks in advance for any assistance or pointers.

Kind regards,

Eric Pement - pemente[at]northpark[dot]edu