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A widget (also graphical control element or control) is an element of interaction in a graphical user interface (GUI), such as a button or a scroll bar. Controls are software components that a computer user interacts with through direct manipulation to read or edit information about an application. User interface libraries, such as e.g. GTK+ or Cocoa, contain a collection of widgets and the logic to render these. Each widget facilitates a specific type of user-computer interaction, and appears as a visible part of the application's GUI as defined by the theme and rendered by the rendering engine. The theme makes all widgets adhere to a unified aesthetic design and creates a sense of overall cohesion. Some widgets support interaction with the user, for example labels, buttons, and check boxes. Others act as containers that group the widgets added to them, for example windows, panels, and tabs. Structuring a user interface with widget toolkits allow developers to reuse code for similar tasks, and provides users with a common language for interaction, maintaining consistency throughout the whole information system. Graphical user interface builders, such as e.g. Glade Interface Designer, facilitate the authoring of GUIs in a WYSIWYG manner employing a user interface markup language such as in this case GtkBuilder. It automatically generates all the source code for a widget from general descriptions provided by the developer, usually through direct manipulation. == History and use == Any widget displays an information arrangement changeable by the user, such as a window or a text box. The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given kind of data. In other words, widgets are basic visual building blocks which, combined in an application, hold all the data processed by the application and the available interactions on this data. GUI widgets are graphical elements used to build the human-machine-interface of a program. GUI widgets are implemented like software components. Widget toolkits and software frameworks, like e.g. GTK+ or Qt, contain them in software libraries so that programmers can use them to build GUIs for their programs. A family of common reusable widgets has evolved for holding general information based on the Palo Alto Research Center Inc. research for the Xerox Alto User Interface. Various implementations of these generic widgets are often packaged together in widget toolkits, which programmers use to build graphical user interfaces (GUIs). Most operating systems include a set of ready-to-tailor widgets that a programmer can incorporate in an application, specifying how it is to behave. Each type of widget generally is defined as a class by object-oriented programming (OOP). Therefore, many widgets are derived from class inheritance. In the context of an application, a widget may be ''enabled'' or ''disabled'' at a given point in time. An enabled widget has the capacity to respond to events, such as keystrokes or mouse actions. A widget that cannot respond to such events is considered disabled. The appearance of disabled widget is typically different from an enabled widget; the disabled widget may be drawn in a lighter color, or may be visually obscured in some way. See the image to the right for an example. Widgets are sometimes qualified as ''virtual'' to distinguish them from their physical counterparts, e.g. ''virtual'' buttons that can be clicked with a pointer, vs. physical buttons that can be pressed with a finger. A related (but different) concept is the desktop widget, a small specialized GUI application that provides some visual information and/or easy access to frequently used functions such as clocks, calendars, news aggregators, calculators and desktop notes. These kinds of widgets are hosted by a widget engine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Widget (GUI)」の詳細全文を読む スポンサード リンク
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