[Paraview] Composite Datasets (bug?)

[John Biddiscombe]

Further to my earlier questions...

I have a filter with 2 inputs. Both are allowed to be vtkDataSet type. 
(I'm using 2 input ports, rather than a single port with multiple inputs)

If I select dataset A, then create my filter, it allows me to place 
dataset A on both inputs, but dataset B won't appear in the pop-up 
menu's. If I select Dataset B, then create the filter, dataset B can be 
put on both inputs, but not dataset A.

I suspect that in the code which checks which type is permitted as an 
input, their must be some kind of bug in the logic and index 0 or 1 is 
not being correctly checked.

Whereabouts in the Paraview Code should I look to try to fix this (or at 
least understand what's going on).

thanks

JB

(NB, Paraview also core dumps if you try to create a filter with none of 
the permissible input types in existence - by which I mean, suppose 
input 1 is vtkDataSet, but input 2 must be polydata - if you instantiate 
the filter when no vtkPolydata datasets exist, Paraview core dumps - 
though it allows the creation because the presence of a vtkDataSet type 
obviously fools it into thinking that it's allowed).