XLEFF is an XML layout Engine for Flash. The main function provided by XML layout engine is generating a component-based UI (user interface) by using an XML description written by you. Because of the XML layout engine, actionScript developer does not need to produce any code for generating the UI and can focus on the application logic producing business objects that simply use the UI dynamically created by the engine. You can get more detail information and download it in following URL. By the way XLEFF is an open source project.