The Design Window is a representation of how your currently active widget hierarchy should look and behave within your application. It is an active dialog, so you can try out, for example, all the buttons, scroll bars, or text fields to get a feel of how the user of your application will have to interact with your program.
The currently selected widget will usually be highlighted in the Design Window as well as in the widget hierarchy. The only exception to this rule are any gadget children of composite convenience widgets, for example the push buttons of the Selection Box widget.
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If a Design Window is hidden, it can be displayed again by clicking on the dialog shell icon in the design area or the window holding area.
You can use links to prototype the behavior of your dialogs, as well as their appearance.
See also: