Discussion: Overprint of map colours in Condes?

I'm sure this has been talked about before, but I can't seem to make it work:

how do I get the map colours to create the overprint effect in Condes? I'm not talking about the overprinting of the course - that bending works just fine. I am talking about the actual colours in the map should blend instead of "knocking-out" the colour below. For example, when a contour line crosses an area of green, it should get darker in colour due to overprinting of the green and brown. I see in OCAD it simulates this on screen in Spot Color mode, but for the life of me I can't get Condes to do it in any output.

EDIT: Oh, wait, nevermind - I finally found it. There is a check box under Canvas...Map... "Use overprint for colors marked "overprint" in OCAD map". Neverfails, you find the answer as soon as you ask.