Hi all,

I’m struggling with the font used in metapost. The only way to
actually change it appears to be enclosing the mp graphic in two
statements of \setupbodyfont[…] -- which I need to avoid. In the
following example, the background text should be typeset (drawn)
as lm sans, whereas the main font should be left untouched
(serif).

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\startMPenvironment %[global]
  \switchtobodyfont[sans]
  %\setupbodyfont[sans]
\stopMPenvironment

%\start\setupbodyfont[sans]
\startuseMPgraphic{bg}
  verbatimtex \setupbodyfont[sans] etex ;
  draw btex I wanna get rid of those serifs! etex
    xysized (21cm, 5cm) withcolor blue ;
\stopuseMPgraphic

\definelayer[bg][x=0,y=0,width=\paperwidth,height=\paperheight]
\setlayer[bg]{%
  %\setupbodyfont[sans]
  \useMPgraphic{bg}
}
\setupbackgrounds[paper][background=bg]
\setupbackgrounds[state=repeat]
%\stop

\starttext
\dorecurse{42}{I’d really like to keep my serifs! }
\stoptext

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Wrapping the mp code inside a group is fatal.
\[start|stop]MPenvironment doesn’t seem to have an effect at all
unless called with the “global” flag -- in which case it will
change the main body font as well. Also, inside mp’s
“[verbatim|b]tex ...  etex” font switches refuse to work.

I’m really puzzled here, any hints? Thanks in advance
Philipp