[Paraview] Optional input and Change input behaviour

[Jérôme]

Hi,
I wrote a filter with 3 inputs, one being optional.
The first time I update the filter, if I don't set any input to the
optional one, all is ok. Then I "Change input" from the pipeline
browser, set an input to the optional one. All is ok as well.
Problem is: I want my optional input back to "no input". How can I do
that from the "Change input" panel?

Thanks!
Jérôme