many thanks for your prompt reply.
I am sorry for my bad description of the problem. My goal is finding the (x y) coordinates of all the shapes intersecting a ruler from all (or some) layers. Imagine you want to create the equivalent cross section of your biased layout...
I played a little with dbGetTrueOverlaps(), but I didn't get the desired result when the ruler intersected a polygon or a path.
Now I am experimenting with dbLayerAnd() and the results are pretty good.
I create a new rectangle starting from the ruler bBox, then I apply dbLayerAnd() between all the objects I need and this new rectangle, and finally I use the bBox coordinates of these new objects for my my needs...
It is likely there is a faster and more elegant solution... but this is my very first skill code :)
Now I have to learn two basic things:
1) is it possible to select shapes inside an instance without flattening it?
2) how can I select shapes from a single layer?
I'll keep you posted with my progress ;)
Thanks again for your help. I am finding all your replies very helpful!