Hi Wojciech,
Regarding to create Usecase kind of Diagram, The instances of Node can be used to represent the UseCase. Instances of LineConnector can be used to represent the dependency between Nodes(UseCases) by specifying the HeadNode and TailNode property of the LineConnector.
With Regards to customize the appearance of the LineConnector, we have provided the custom options for LineConnector like LineConnector style, DecoratorShape. LineConnector can be connected to a specific position in the Node, by connecting with ConnectionPorts.
For more details , please refer Online help Documentation
Link:
http://help.syncfusion.com/ug_92/User%20Interface/WPF/Diagram/index.htm and Navigate to the topics as shown below.
1. Nodes: Concepts and Features > Nodes
2. LineConnectors: Concepts and Features > LineConnectors
3. Customizing the LineConnector: Concepts and Features > LineConnector > Customize Line Connectors
4. ConnectionPort: Concepts and Features > Connection Port
Please create the Direct-Trac incident ,to get quick update and to have better follow up.
Link:
http://www.syncfusion.com/account/Please let us know if you have any further queries and we will be happy to help you out.
Regards,
Ramya