why this happens:
After a specification of the foregroundcolor the figures are behind a
framed color.
\setupframed[offset=2mm,
corner=round,
background=color,
backgroundcolor=blue,
foregroundcolor=yellow,
frame=off,
strut=no,
align=normal, location=top,
width=\textwidth]
For example, is this case my \placefigure[right,nonumber,2*hang]
{}{\externalfigure[ostrichhead][width=5cm]} is behind a yellow framed
rectangle.
Jorge