Disclosure widget


A disclosure widget, expander, or disclosure triangle is a graphical control element that is used to show or hide a collection of "child" widgets in a specific area of the interface. The widget hides non-essential settings or information and thus makes the dialog less cluttered.
The disclosure widget may be expanded or collapsed by the user; when this occurs, the containing window may be expanded to accommodate the increased space requirement. The state of the widget is often signified by a label with a triangle next to it, pointing sideways when it is collapsed and downward when it is expanded, or a button with an arrow pointing downward when it is collapsed and upward when it is expanded. Some disclosure widgets can appear as a plus button when collapsed and a minus button when expanded.
In some implementations, the widget may be able to remember its state between invocations; this may increase user familiarity with the interface. In other implementations, the widget may disappear when clicked in order to make room for the newly revealed controls; this state is not remembered.
Some user interface designers call this widget a "norgie", or "twistie".