Joachim Kruithof

`view(slicing_planes = True)` has no effect when used with `vtkXMLUnstructuredGridReader`

2

Here is a sample code to reproduce the issue ```Python # https://github.com/InsightSoftwareConsortium/itkwidgets/blob/master/examples/vtkUnstructuredGrid.ipynb import vtk import itk from itkwidgets import view path_vtu = "../internal/results/internal_004_3D_plot_and_animate/results.vtu" reader = vtk.vtkXMLUnstructuredGridReader() reader.SetFileName(path_vtu) reader.Update() volume =...