overprint bug (mkiv)

[Peter Rolf <indiego@gmx.net>]

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Hi Hans,

overprinting is broken under very special conditions. You need to add 
framed content with a defined mp overlay as background and *deactivated 
frame* to a layer (last of the four pairs in the example). The text of 
the last pair is written in the same \GSoverprint group (in this case 
the \GSknockout is even missing). Very obscure.

Have fun,

Peter


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\setupcolors[state=start]
\setuppagenumber[state=stop]

\pdfcompresslevel=0
\pdfobjcompresslevel=0

\startuniqueMPgraphic{FOO}
    fill OverlayBox withcolor lightgray;
\stopuniqueMPgraphic

\defineoverlay[FOO][\uniqueMPgraphic{FOO}]
\definelayer[BAR]



\starttext

% OK
\setlayer[BAR][x=0mm,y=0mm]
{\framed[background=color,backgroundcolor=lightgray,frame=off]
{\startoverprint first one\stopoverprint}}
\setlayer[BAR][x=50mm,y=0mm]
{\framed[background=color,backgroundcolor=lightgray,frame=off]
{\startoverprint second one\stopoverprint}}

% OK
\setlayer[BAR][x=0mm,y=15mm]
{\framed[background=color,backgroundcolor=lightgray,frame=on]
{\startoverprint first one\stopoverprint}}
\setlayer[BAR][x=50mm,y=15mm]
{\framed[background=color,backgroundcolor=lightgray,frame=on]
{\startoverprint second one\stopoverprint}}

% OK
\setlayer[BAR][x=0mm,y=30mm]
{\framed[background=FOO,frame=on]
{\startoverprint first one\stopoverprint}}
\setlayer[BAR][x=50mm,y=30mm]
{\framed[background=FOO,frame=on]
{\startoverprint second one\stopoverprint}}

% ( layer + overlay + frame=off ) is buggy
\setlayer[BAR][x=0mm,y=45mm]
{\framed[background=FOO,frame=off]
{\startoverprint first one\stopoverprint}}
\setlayer[BAR][x=50mm,y=45mm]
{\framed[background=FOO,frame=off]
{\startoverprint second one\stopoverprint}}


\flushlayer[BAR]

\stoptext

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