View source for Selection in an application over VTK

==Use Case Description==
# I have two windows in the application. A VTK (QVTK) window with a vtkDataset, and a QTreeView.
# I want to select something in my VTK view and have the selection show up in my Qt View
# I want to select something in my Qt view and have the selection show up in my VTK View
# I want to select something in my Qt view and create a new vtk dataset that is a subset of the current dataset.
So I will need functionality in VTK and a utility library that will allow me to 'get' and 'set' the current selectionSet from my application. I will also need a filter in VTK that takes a selectionSet and a vtkDataset and produces a vtkDataset. This filter will be like vtkThreshold. Also it will need to have an In/Out ivar... meaning that I may want the selected items or everything but the selected items to come out as output.