| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: object
Returns true if object is a window or a menu that
is open (and therefore still usable), and otherwise returns nil
. This may useful for determining whether the
owner or parent of a window is a window rather the
screen, for example, or whether a known window or menu is still open.
Specifically, true is returned if the object is a cg-stream
of the basic-pane
class or the menu
class, and the stream has not been closed
(due to close being called on
it), and the process that created it has not been killed.
If an open window or menu's creation-process is killed, then the
window is no longer usable, but Common Graphics may not realize that
and will continue to regard the window as being an open stream.
windowp will catch this
situation, though, and will return nil
after
calling close on the stream so
that it is properly closed.
See also screenp.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |