Filter with Multiple Inputs is only usable on one dataset
A custom filter with multiple inputs is sometimes disabled. I can select one dataset in the pipeline browser and the filter is disabled in the filter menu, but selecting the other dataset will allow to apply the filter.
It seems that only the "first" input is used to the check if the filter can be used on the currently selected dataset. First in means of alphabetical order of the input name. This is especially bad when the input with the "first" name is meant as optional one, and the datasets I want to look at do not even have such an input type. In this case the filter cannot be used at all.
By trying to debug this, I found a TODO note within the source for this issue: https://gitlab.kitware.com/paraview/paraview/-/blob/v5.9.0/Qt/ApplicationComponents/pqFiltersMenuReaction.cxx#L228
(I noticed that the inputs are stored in a std::map using the name as key. Therefore the "strange" behavior using the the "first" name at least has a consistent explanation.)
It would be nice if a all inputs of a filter are checked, before disabling it in the filter menu.