We have released JDiagram version 3.1. It contains the following new features:

Support for custom arrowheads
The type of the HeadShape, BaseShape and IntermediateShape properties of DiagramLink has been changed from enum ArrowHead to class Shape, which is also used to define ShapeNode shapes. The ArrowHeads class now exposes Shape definitions that correspond to the ArrowHead enumeration members from previous versions. It is also possible to set any other predefined or custom shape accessible through the fromId method as an arrowhead. When used for arrowheads, position (50, 0) in the shape definition corresponds to the arrowhead's tip point.

Topological graph layout
If the underlying graph if acyclic, TopologicalLayout arranges the nodes linearly in such a way that each node comes before all destination nodes of its outgoing links. The links are drawn as curves above the chain of nodes, with their height proportional to the distance between the nodes. If the graph is not acyclic, the layout algorithm finds an ordering with a minimal number of back links, and draws the back links below the chain of nodes.

Miscellaneous
~ Shadows can be painted using any brush type and not only in solid color. The ShadowColor property has been replaced by ShadowBrush.
~ Custom drag-and-drop implemented for ShapeListboxApplet, since recent versions of the JRE do not allow drag-and-drop operations in applets.
~ Granularity property added to QuickRouter.
~ ShowToolTips property added to DiagramView

Registered customers with an active upgrade subscription can download the licensed version from the clients area on our site. 
    
A trial version is available for download here: 
https://www.mindfusion.eu/JDiagramTrial.zip
    
Enjoy!