I think that should show it - It's a white backdrop rectangle that entire underlays view and covers the lower z-order views.
I'm leaning to #3 as Postscript output tends to be opaque and would require a clipping boundary to prevent overstamping; PTC has not treated Postscript well, certainly not well enough to suggest they would fix their raw Postscript output for external consumption. Adobe added transparency support to Postscript, but it was a late addition.