How do I model the static and a dynamic aspects of the User Interface of a system?
Static aspects of the user interface can be modelled by identifying boundary classes. The candidate classes are generally identified from sequence and collaboration diagrams. Among the candidate UI classes are all the objects which are directly interacted upon by the actor. These boundary classes represent the static aspects of your GUI development.
The dynamic nature of your GUI can be depicted in your sequence and collaboration diagrams. Sequence diagrams capture the dynamic nature of your object interactions over a certain period of time, while collaboration diagrams depict the behavior of objects in the context of various other associated objects.