I suggest a variation that accomplishes the same end. The
markup should instead indicate that the element it applies
to is intended for interactive purposes rather than part of
the document proper. Then we can let the printing program
decide not to render elements which are interactive on the
grounds that the human reading the printed version would
not be able to interact with the paper.
On the other hand as D. Ragget points out this specific kind
of artifact Hoesel was thinking of gets special treatment in
HTML+ so the need will go away. And also, it seems to me
that one might wish to print the littlke arrows anyway, as
for instance when you want to capture a screen snapshot for
presentation elsewhere. (On the other hand, perhaps in that
case one should use a screen capture tool, not expect a WWW
browser to print it for you that way. I complely agree that
I don't want the little arrows in my book.)
PS. The assumption that paper is not interactive will
become false someday, see the article by P Wellner in
the July CACM (p 86): Interacting with Paper on the DigitalDesk.