\setuppagenumbering[state=stop]
\definelayer[mybg]
[
repeat=yes,
x=0mm, y=0mm,  
width=\paperwidth, height=\paperheight,
]
\setlayer[mybg]{\externalfigure[cow][width=\paperwidth,height=\paperheight]}
\setupbackgrounds[page][background=mybg,state=repeat]
\setupindenting[yes,small]
\startsetups background:default
\setupbackgrounds[page][background=mybg,state=repeat]
\stopsetups
\startsetups background:void
\setupbackgrounds[page][background=]
\stopsetups
\starttext
\dorecurse{7}{\input knuth}
\page
\setups[background:void]
\dorecurse{8}{\input tufte}
\page
\setups[background:default]
\dorecurse{7}{\input knuth}
\page
\stoptext

works with a local image (say, if "cow" is in the same folder as the main file), but it doesn't find sample images (cow, hacker, etc.). Is that a bug or an intended result? Thank you in advance.

Best regards,

Jairo