The tools in the Graphical Toolbox are based on a technology called the Panel Definition Markup Language, or PDML. PDML is based on the Extensible Markup Language (XML) and defines a platform-independent language for describing the layout of user interface elements. Once you have defined user interface panels using PDML, you use the runtime API to display them. The API displays your panels by interpreting the PDML and rendering your user interface using the Java Foundation Classes.
@since v4r4m0