[vtkusers] questiong abt setting trackball style as default

[Tracy]

Dear everyone,

I developed my VTK code with GUI design under .NET environment . 

But the question is I can not  toggle between joystick

(position sensitive) and trackball (motion sensitive) styles

after pressing "j" or "t" . 



Does someone know where I am wrong , and please tell me

how I can set the default vtkInteractorStyle as  trackball style?

Thanks in advance

Regards

Tracy