'''BAD NEWS!!! Kitware will deprecate Tcl/Tk support inside VTK''', see http://markmail.org/message/tfnjj55dwpypzrao?q=ANN:+Deprecating+Tcl%|%announcement%|%, and https://gitlab.kitware.com/vtk/vtk/merge_requests/3582%|%merge request%|%

Extract from the announcement:
===
Hi,

I've made an MR to deprecate Tcl for 8.1 and remove it for 9.0. There
was discussion before the hackathon on it, but it seems to have been
missed.

Deprecating it is easy, but there are related modules which are now in
question: ...
===