[NTG-context] External linked PDF in new window?

I have a showcase-type document in which I have thumbnails of external PDFs which should link to the originals when clicked: \goto{\externalfigure[france][page=2,height=.6\textheight]}[france::] But clicking on this replaces the main document by the new one. I notice that Hans' showcase PDFs (the show-xxx series) don't exhibit this behaviour. There linked documents open in their own window. How's that done?