Hi,

I asked this question some time ago:
https://tex.stackexchange.com/q/354731/2867
Today I found out about viewer layers. Sadly they seem to be buggy in the
ConTeXt version in TeXlive 2019.52575
When I compile the following document, the “view” layer seems to gobble up
the rest of the document: Hiding it makes “More text” vanish.
Also, I don’t know if [state=stop,printable=yes] does what I want, i.e.
being visible by default on print media. If not, how to achieve that?

Best, Philipp

\defineviewerlayer[print][state=stop,printable=yes]
\defineviewerlayer[view][state=start,printable=no]

\def\viewcolor#1#2{%
    \startviewerlayer[view]\color[#1]{#2}\stopviewerlayer%
    \startviewerlayer[print]\llap{#2}\stopviewerlayer%
}

\starttext
Hi!

\viewcolor{red}{This is only red on screen}.

More text.
\stoptext