[Paraview] Bug? - ExtractedSelection is mapped between Extracted Blocks

[redkite]

Hi,

I understand that objects in a vtk pipeline will be updated if something 
earlier changes, but I can see no use for this behaviour (and it's quite 
a pain to me ;). To replicate:

1) Load the can.ex2 example and apply the 'Extract Block' filter.
2) Navigate to the ExtractBlock/'Block indices' menu and switch on 
'Unnamed block ID 1' so you can see the semi-circular can object.
3) Click the 'Select Points On' rubber-band selection button and draw a 
rectangle of points on the can.
4) Click the 'Extract Selection' button.
5) Go back to the ExtractBlock/'Block indices' menu, switch off 'Unnamed 
block ID 1' and turn on 'Unnamed block ID 2'

You will see that the extracted selection is mapped to apparently 
arbitrary points in or on the second block (you may need to change 
opacity to see the mapped points). Other similar but strange behaviour 
occurs if you select across blocks and switch to view just one or a few 
of them.

I note that if I obtain the pqSelectionManager I can clear the 
selection, but as the docs say, the selection still exists somewhere in 
the vtk code. Is there a better way to control this action?

(Tested with ParaView 4.1 and Windows and Ubuntu, and 4.2 on Ubuntu.)

Thanks,
Richard

ps
I tried searching through the archives for block/selection issues and 
I'm a bit surprised not to find anything like this before.... though it 
may be related to issue raised by Robert Ainsworth ?? [so I've just cc'd 
this to him]
(http://paraview.markmail.org/message/z4eq4hj2zerrwste?q=selection+on+blocks&page=3)