[vtkusers] Deleting vtkImageWriter

[Gib Bogle]

This is probably a dumb question.

Why is it that although this works fine

vtkSmartPointer<vtkTIFFWriter> tifwriter = tkSmartPointer<vtkTIFFWriter>::New();
tifwriter->SetInputConnection(w2img->GetOutputPort());
w2img->Modified();
tifwriter->SetFileName("zzz.tif");
tifwriter->Write();

if I attempt then to delete tifwriter with
tifwriter->Delete();

the program crashes?  Is it not necessary to delete the writer?