handle-scrolling-keys

Arguments: window

Returns whether a window or widget will automatically interpret certain keystrokes for scrolling. The value may be set by passing the handle-scrolling-keys initarg when creating the window or widget, or any time later by calling (setf handle-scrolling-keys).

window-or-widget should be either a regular window (an instance of basic-pane or any of its subclasses other than widget-window) or a lisp-widget. This facility does not apply to os-widgets because they always handle their own scrolling internally.

If the value is nil, then the window or widget will not scroll when the usual scrolling keys are pressed; an application would need to handle this itself in a virtual-key-down method. If the value is :page, then the PageUp and PageDown keys will scroll the window vertically by a page, or horizontally by a page if the control key is held down. If the value is :vertical then the up and down arrow keys will scroll by a line vertically, in addition to PageUp and PageDown being handled vertically as with :page. For any other true value, the left and right arrow keys will scroll horizontally by a line, in addition to all of the :vertical keys being handled. The default value is nil.

The scrolling is done by calling scroll. The scrolling distance that is passed to scroll is found by calling scroll-increment.

This facility is implemented in the default virtual-key-down method for basic-pane. If a more specific virtual-key-down method overrides the default for these keystrokes, then the automatic scrolling will not be done.

Copyright (c) 1998-2009, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 8.1. This page is new in the 8.1 release.
Created 2007.4.30.