Version 1.5.0-beta6 is now available at GoJS - Build Interactive Diagrams for the Web.
The most recent new features support additional ways to scroll or pan the diagram. Increase the area to which the user can scroll or pan by setting Diagram.scrollMargin to a non-zero Margin. Allow “infinite scrolling” by setting Diagram.scrollMode = go.Diagram.InfiniteScroll.
You can also limit the values that Diagram.position and Diagram.scale can take, by setting the functional property Diagram.positionComputation and/or Diagram.scaleComputation.
There is a new sample demonstrating some of these features at Scroll Modes GoJS Sample.