[Paraview] my custom filter only inserts at end of pipeline

[FISSELL at pitt.edu]

Hi,

I made a custom filter that takes polydata as input.  When I select it
from the menu
it always goes to the end of the pipeline, regardless of what pipeline
step is selected/highlighted.
If I have a polydata dataset selected midway thru the pipeline I'd like my
filter to jump in as a
sub-step of the selected step, the way the threshold filter does.
Is there some XML or C++ magic I need to add for this to happen ?

thanks
Kate