from initial issue (prev release):
To reproduce:
1. create two class diagrams, e.g. c1 and c2.
2. add an classs element.
3. opent one diagram.
4. right click the diagram view and choose Associate With... menu item.
5. In the Associate dialog window, search the other class diagram by name.
6. select the class diagram in the list and click do associate button.
7. search the class element by name.
8. select the class element in the list and click do associate button.
9. close the dialog window.
10. On the project tree, check the relationshps of the class diagram.
Notice there is no  reference shown under the class diagram.