Hi,

this sample shows that the image in a layer in header disappears if showframe is
set.

\setupexternalfigures[location=default]
\definelayer[Cow]
[x=0, y=0]

\setlayer[Cow]
[x=10em, y=0mm]
{\externalfigure[cow][height=\lineheight]}
\setupbackgrounds[header][background=Cow]

\showframe

\starttext
\input knuth
\stoptext

Mit freundlichen Grüßen
Jan Ulrich Hasecke

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