Thanks for taking the trouble for what was really simple, but seems undocumented (?)
It does, and then all the offsets etc, seem to work in pixels as well. 

eg.

\definelayer [topmatter] % name of the layer
[x= 0 px, y=20 px, % from upper left corner of paper
width=\paperwidth, height=\paperheight] % let the layer cover the full paper

Ian

On 24 February 2011 09:47, luigi scarso <luigi.scarso@gmail.com> wrote:
On Thu, Feb 24, 2011 at 10:40 AM, Ian Lawrence <physics.rooted@gmail.com> wrote:
> Morning all,
> Quick question.
> I want to design a screen document at 1024 by 768 pixels, so ideally work in
> pixels as units, and not mm / cm.
> I know pdfs are scalable and about \setuppapersize[S6][S6], but I'd prefer
> to work in pixels (I have swfs / images to embed, and these come in x by y
> pixels).
> Anyone have an easy answer?
\definepapersize[Screen][width=1024px,height=768px]
\setuppapersize[Screen][Screen]

You should check if it's ok, I'm not sure.
--
luigi
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