<\body> Most of the user interface to is dynamically created from within the interpreted code. New menus and buttons can be added, or the existing ones reused and rearranged, even the main editor can be embedded anywhere. Imagine you want to implement some feature which requires interaction with the user. One possible approach is to use the facility , which according to the user's preferences will either popoup a dialog or ask in the footer bar, based in metadata you provide inside your 'd function. See ``'' for more on this topic. However, automatically generated content is not always the best approach, so you might want to explicitly design your interface placing it inside a complicated dialog. The following sections should help you with this. <\traverse> \; team.> <\initial> <\collection>