vtk

I've seen this come up in the discussions a few times. We need to document that the threshold filter is a CELL-wise operation.

Ref pyvista/pyvista#1815 (comment) and pyvista/pyvista#1758 (comment)

Cancelling "Create new X as ..." dialogue creates new object with the default name (as if from "Create new X"), but clicking Cancel should not produce any object.
I think this happens in several modules, with different types of object, including Table and Volume.

Steps to reproduce

Invoke "Create new Table as ..." dialogue, such as for the Output table of the **Segment St

Add a PolyDataIO based on the VTK::IOPDALmodule:

https://github.com/Kitware/VTK/tree/master/IO/PDAL

Steps (a complete example can be found here):

0. Verify that the test suite runs and passes

Using drag and drop can be annoying if nodes are far apart and zoomed out.