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