I have BlueJ for Macintosh, 4.0.1.
I coded a project with one class implementing an interface.
In the project window (package window?), the arrow between the class and the interface shows with a solid line, the same as the "extends" arrow. It should be a broken line for "implements" in UML.
I can open the same project in 3.1.7, and the correct arrow is shown.
Can I attach a file here? A screen shot?