Bruce,
While trying to debug a program I was getting unexpected results (so what's new?). I had chosen a very poor way to display objects, some visible and some not. The clue to the behavior came when I realized that compounding a list of visible and non-visible objects turns on the visibility for all the objects that are being compounded, ie: .visible = True for all the objects in the compound.
A note about this behavior in the docs might help some beginner folk, like me.
My solution was to create, using clone(), only those objects that needed to be visible. In my case, that eleminated thousands of non-visible objects, greatly increasing display speed.
Thanks for all you do.
Bennett Weaver