vtkPicker, vtkPointPicker and vtkCellPicker do not handle vtkCompositePolyDataMapper input
vtkPicker::MarkPicked, vtkPointPicker::IntersectWithLine and vtkCellPicker::IntersectActorWithLine assume that the mapper can return a vtkDataSet. This is not true when using vtkCompositePolyDataMapper, and picking will cause the application to crash.