Version 1.5.0-beta6 is now available at http://gojs.net/beta.
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 http://gojs.net/beta/samples/scrollModes.html.