I've been trying to use layers for a simple logo that repeats on all pages.
Something along the lines of the code below:

\definelayer[mybg][x=0mm, y=0mm,width=\paperwidth,
height=\paperheight,repeat=yes]
\setlayer       [mybg]
                [hoffset=1cm, voffset=1cm]
                {\framed[frame=on, width=3cm,
height=2cm]{\externalfigure[cow][width=1cm]
}}
\setupbackgrounds[page][background=mybg]

\starttext
\dorecurse{6}{\input tufte\par}
\stoptext

It works as expected using Mk II but does not work under Mk IV: The layer
appears only on the first page.

Please Help,
Derek