Documentation?

[Alan Cox]

> And in the past, we never had the viewing distance in X11's design: our
> presumption was then always desktop monitors, viewed at the "usual"
> desktop distance).  It is entirely missing from the core protocol.

One problem is that this is application dependant. I will be at "normal
viewing distance" for typing and editing. However I suspect I am not
alone in having other apps (eg the mail status icon, movie players, ...)
that I view with the chair further away (working on other parts of the
desk) or when walking past the display from a distance

Nor I suspect will tracking help this - a display that zooms based on
user distance is probably going to induce motion sickness rather than joy