I need margin notes in a doublesided page environment in MKIV. 

The following:
\setuppagenumbering[alternative=doublesided]
\setupinmargin[location=both]
\starttext
\inmargin{n1}\input knuth\inmargin{note 1}
\page
\inmargin{n2}\input knuth\inmargin{note 2}
\page
\inmargin{n3}\input knuth\inmargin{note 4}
\stoptext

works in MKII. In MKIV, however, all the margin notes are on the left. So how can I get this right in MKIV? 

Alan