Override this method to get notified when the drag activity is stepping.
During a drag sequence an activity is scheduled that runs continuously while the drag sequence is active. This can be used to support some additional behavior that is not driven directly by mouse events. For example PZoomEventHandler uses it for zooming and PPanEventHandler uses it for auto panning.
PDragSequenceEventHandler Class | UMD.HCIL.Piccolo.Event Namespace