Managing user interfaces
One of the biggest problems in the development of any application is the interaction with the user. In whatever way the user interacts with the application, the code almost always ends up being complex and difficult to maintain. This is true for graphical interfaces and for command line consoles.
The user interface problems
The main reason for this complexity lies in the management of three aspects of the interaction between the user and the application: the state, the logic, and the synchronization.
The state is the set of information that represents the current picture of the user interface. It determines what the user sees at a given time and how it can interact with the application.
The logic is the set of operations that can be done on the elements of an interface in order to show or hide data or to make validation. It may be very complex depending on the type of processing to be performed on the data presented to the user.
The synchronization concerns those activities...