| Allegro CL version 6.2 Unrevised from 6.1 |
The class of all control windows that are implemented in the operating
system (the related lisp-widget-window
class is for
controls implemented in Lisp). An application can usually use the
various instantiable dialog-item classes (also called controls or
widgets) without concerning itself with their associated widget-window
or lisp-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 or lisp-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 addition, to receive low-level window events for widget-windows (which are implemented in the operating system) but not for lisp-widget-windows (which are implemented in lisp), the function subclass-widget must be called on the widget-window after it has been created by adding a dialog-item to a parent window. Note that this function has nothing to do with CLOS classes, but instead performs what Microsoft calls "subclassing" to intercept low-level window events that are normally handled within the operating system by the control's own window procedure there.
Copyright (c) 1998-2002, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 6.2. This page was not revised from the 6.1 page.
Created 2002.2.26.
| Allegro CL version 6.2 Unrevised from 6.1 |