This is only a EclipseUML 2008 feature.
This feature is available at Interface and Diagram level.
Interface level will just change the selected interface while diagram
level will change all interfaces included in the diagram.
To activate this feature at Interface level select the Interface >Interface as Lollipop
To activate this feature at class
diagram level select the diagram
background > Interface as Lollipop
Here is the new Interface view inside
the Class diagram
