[vtkusers] how to update a renderwindow everytime when I change the actor's data by some keypress operations?

[老猫]

Hello, everyone.
  
 I have several actors in a renderwindow.I want to change one actor's coordinate by press some keys. I rewrite a interactorstyle, it can catch my orperation and change the actor's coordinate.By the way,the actor is a set of points.
  
 But how can I show the change in the window without creating a new window .When I press a key,the actor changes its position.At the same time,when some changes happen, I don't want to change the visual angle which I adjusted last time.
  
 Thank you!Best wishes!
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