[vtkusers] Getting an region of interest out of a ImageTracerWidget ?

[Daniel Kornhauser]

In the ImageTracerWidget .py example how can I get from the poly 
instance in the AdjustSpline callback

    The coordinates of points that compose the green line around the 
region of interest ?
    or
    The coordinates of the points inside the the region of interest ?
     or
    I am totally wrong and I should get them from the extract instance ?

                               Thanks.


                                                                   Daniel.