cbk->IV = _imageViewer2XYZ->GetVtkImageViewer2();
interactorstylebaseview->AddObserver( vtkCommand::WindowLevelEvent, cbk );
interactorstylebaseview->AddObserver( vtkCommand::StartWindowLevelEvent, cbk );
cbk->IV = _imageViewer2XYZ->GetVtkImageViewer2();
interactorstylebaseview->AddObserver( vtkCommand::WindowLevelEvent, cbk );
interactorstylebaseview->AddObserver( vtkCommand::StartWindowLevelEvent, cbk );