[NTG-context] heading and a few lines at the end of a page

Hello, sometimes I get a heading and a single line (or two lines) at the end of the page and it does not look good? Is there any way (TeX or ConTeXt) to force pagebreak before heading in this case? Ideally I'd like to be able to specify the count of lines when this should occur. best regards Jan -- Tato zpráva byla vytvořena převratnou poštovní aplikací Opery: http://www.opera.com/mail/