[NTG-context] howto overlayers on section head

I would like to start to experiment some metafun "decoration around(over)" section head and/or page number. Something similar, just for example but I do not want to copy the style, to the one used to produce the metafun manual. From the (small "scale") drawing primitives to the (large "scale") \setuphead I miss an howto that combine the two (specifically I was thinking at a (non-existent) background keyword in \setup to pass an overlay...but likely I am far off) I don't want to be lazy, maybe it is already written in the manuals, but I still miss a certain kick.... so to say... Regards.