[NTG-context] add layer to page

Hi all, I have a vague memory that there was a message (by Wolfgang Schuster?) about this a couple of months ago, but I'm unable to find anything in the archives. What I want: add a layer on top of the current page. This page is created with the simpleslides-module, so it already contains several layers. I want something on top of all that, and I seem to remember that there was some option to say "typeset the current layers + this additional one." Can somebody help my memory? All best Thomas