Disable shift-drag (translate) in TrackballActor interaction style

While in “TrackballActor” interaction style, I would like to allow users to rotate objects around their centers, but not drag them out of position (shift-click), is there an easy way to achieve this?

You should be able to subclass the interactor and then override one of the event handlers - for example, override mousemove and if the shift key is pressed, skip the event. Otherwise pass it down.