I have a load of objects strewn around a diagram according to their own sweet logic, and for *some* of them, I want to draw a horizontal line going from the right hand edge of the object to some globally fixed x coordinate, call it the "margin". So those lines are all different lengths because the objects are all over the place, but their right-hand ends should all be aligned vertically.

This seems quite hard, because that sweet logic is already quite complicated and local to a set of objects in the immediate neighbourhood of the object in question. Somehow I have to tease out a selection of them and process each of them into this line whose properties depend on where the object is from the global perspective.

But how?

Adrian.