Tim via users writes:
Later on, printers and/or drivers seemed to think that my absolute
dimensions related to the page should be applied relative to the
printing margins, instead; and content shrunk down relatively, as well.
It was one hell of an annoyance to try and get printouts to be what
they were supposed to be.
Dunno what to say, except that I've been printing envelopes from
OpenOffice/LibreOffice for decades, using the same .odt file. I've used
several printers along the way. All of them had an adjustable manual feeder
that centered the paper stock in the feed slot, and my envelope.odt has been
unchanged for years. All it is, is a landscape-oriented page with two text
areas, where they would be if a single, standard page gets printed in
landscape format. And it just so happens to print exactly over the envelope,
when it's centered over the page.
I never had OpenOffice/LibreOffice do anything other than that.