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| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version

## os-widget-window

The class of all `widget-window`s that are provided by the underlying window system or operating system. This class is not instantiable. An application can usually use the various instantiable `dialog-item` classes (also called controls or widgets) without concerning itself with their associated `widget-window` classes which are internally instantiated to create the actual windows that appear on the screen for the logical dialog-items created by the application.

But if an application needs to intercept low-level window events that are not exported as one or more of the dialog-item's event-handler properties, then the application should make subclasses of both the `dialog-item` class and the associated `widget-window` class, and then add the needed methods that specialize on the window subclass, such as virtual-key-down or mouse-left-down methods. A widget-device method also should be added to associate the window class with the dialog-item class.

In releases prior to 7.0, this class was named by the symbol `widget-window`. That symbol still exists and still names a class, the superclass of `os-widget-window` (and of `lisp-widget-window`).

A diagram of window and widget classes is shown in Widget and window classes in cgide.htm.

Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.2 page.
Created 2012.5.30.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version