CULLINGOBJSELECTION (System Variable)

Controls whether 3D objects that are hidden from view can be highlighted or selected.

0	No object culling Rolling over 3D objects highlights all 3D objects, including hidden objects. Selecting 3D objects by dragging selects all 3D objects, including hidden objects.
1	Apply object culling Rolling over 3D objects highlights only the objects that are normal in the current view. Selecting 3D objects by dragging selects only the objects that are normal in the current view.