[NTG-context] Double-sided layer

Hello context-community, I have an image as a layer and want it to place on every page of a book with some offset. My minexample: \setlayer[mybg]     [hoffset=2cm, voffset=0.2cm, doublesided=yes] {\framed[frame=off, width=2cm, height=1cm]{\externalfigure[bilder_bearbeitet_png/32.png][width=\textwidth]}} That works in principle, but I want the hoffset to be relative to the cutspace/backspace: different on right and left page, such that the layer is set equally on every page relative to the textbody. In the example above I use "doublesided=yes", but that has no effect. How to achieve proper double-sided behavior? Thank you. Huseyin