With this latest beta release, there are several bug fixes, some documentation improvements, and a new extension, the DimensioningLink. You can see it in the new sample: http://gojs.net/beta/extensions/Dimensioning.html
I seem to have forgotten to post an announcement for beta version 1.6.0-beta5. Well, no matter -- we just put up 1.6.0-beta6, at http://gojs.net/beta.
We've added the Relationships sample, which demonstrates custom rendering of links.
We fixed some bugs in Table Panels involving separators and clipped rows or columns, and a bug involving ellipsis in TextBlocks.
We have improved animation involving collapsing/expanding subgraphs and trees.
We have improved the styling of the documentation pages.
The Space key now cycles through the Diagram.highlighteds collection if it's non-empty; otherwise it will cycle through the Diagram.selection collection if it's non-empty.
The latest beta release has improved the styling of the documentation, documents many previously undocumented methods (especially on the Link class) and includes a few bug fixes.
Read more details about the new features of version 1.6 at GoJS beta version 1.6.0-beta3.