anniexie,
The option of “Class Associations” “Pakage centric’ view etc are only for the outline view. It will just update the hierarchy according to the view selected. It does nothing to the diagram view.
What I’m really want to do is to draw a class diagam with all relationships across different packages. How do achieve this?
I’m not sure what you are looking for here. How is it different from any other class diagram?
Do you mean that you have each package (add resp. classes) in a seperate diagram(s) and you want to link them together? If so you can just drag and drop copies of the classes in a new class diagram and add relationships.