Description of Common Controls :
The control elements distinguish themselves by the fact that they automatically save their own state across server roundtrips, so that the scrolling mechanism of a list, for example, or the explosion and folding of a tree structure do not have to be implemented independently. Rather, the state is managed by the control element itself, so that the developer can concentrate on the actual and important aspects of a Web application, such as the technical sequences or providing the data. The Framework takes over the presentation.