[NTG-context] Index entries messing up page breaks

The manual suggests that you can put index calls between a \section heading and its first paragraph without worry, but for me it breaks the page-breaking mechanism, allowing the section title to end up at the bottom of a page like this: \starttext \section{Tufte} \dorecurse{4}{\input tufte \par} \section{Knuth} \index{Knuth} \input knuth \par \stoptext Is there any workaround/fix? Thanks very much, Duncan