[NTG-context] Step repeat pdf in overlay

Hi all, I've created a small (15x15 mm) tile image (actually a vector PDF) that I'd like repeat on a cover page but I'm at a bit of a loss as to how to step repeat* the image. Here is what I have: \useexternalfigure[cover][background] \defineoverlay[cover][{\externalfigure[cover][repeat=yes]}] \starttext \setupbackgrounds[page][background=cover] \startstandardmakeup My title goes here \stopstandardmakeup \stoptext As one might expect, I get a tiny tile in the centre of the page. Any ideas? Cheers, Randall * By 'step repeat' I mean something like: http://www.excourse.com/steps/ http://www.adobe.com/education/pdf/id_tutorials/suzanne/step_and_repeat.pdf