[vtkusers] Reduce the size of this sphere/ball of vtkBoxWidget

[wassim_belhadj at topnet.tn]

Hi,

I'm using  vtkBoxWidget for clipping a volume and view only subregion of
the data.

To manipulate (orient and position of bounfing box) the vtkBoxWidget, we
must use the red sphere/ball
that  exist in each plan of the box.  

My problem is  that when I zoomed my volume this sphere/ball becomes large.

Is there  a way to reduce the size of this sphere/ball.  

Thank you in advance.
Best regards, 
wassim