[vtkusers] trackball interactor strange behaviour

[N Smethurst]

Hi all.

Has anybody else noticed this strange trackball interaction behaviour? 
After doing a press-move-release with the mouse, the interactor continues 
to follow the mouse movements after the button has been released. The 
additional time spent following the mouse after the button has been 
released seems to be proportional to the time spent holding the button 
down during the previous interaction.

Due to this, it is necessary to avoid moving the mouse for a period of time 
after having positioned the scene, in order to avoid unintentionally 
repositioning it again. This is most annnoying.. Is this a bug or have I 
configured something incorrectly in VTK?

Regards

Nick