os-widget-window

The class of all widget-windows 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.

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This page was not revised from the 9.0 page.
Created 2015.5.21.