[vtkusers] ImplicitPlaneWidget Position of the normal vector

[Luca]

Hello!

I've to make a program like the example in 
Examples\GUI\Python\ImplicitPlaneWidget (but made in c#.net using Activiz).

1) I don't know how to set the position of the normal vector. I see 
clicking with the left mouse button on the small ball representing the 
normal vector I can translate it and I can position it where I want, but 
how to "initialize" the position?

2) I can move the plane using mouse clicking on the arrow of the normal. 
How to do if I don't want to use another device (keyboard or joystick) 
to interact with the plane? How could I modifify the interactor?

Thanks so much!