14.3.6 Adding menu components Check components

Like radio components, check components place constraints on the behavior of their child items when selected. Each item in a check component either returnst ornil, and repeatedly selecting a given item toggles the value that is returned. Thus, check components allow you to define groups of menu items which can be turned on and off independently.

An example of a check component in the Common LispWorks environment are the commands in the Works > Customize menu, available from any window in the environment.

Click Check Component in the button bar of the interface builder to add a check component to the current interface. Like other components, check components must be added as the children of a menu, and are not visible until items have been added. Use the Item button to add an item to a check component; it is automatically given the correct menu type. Note that you cannot add a submenu as an item in a radio component.

Like radio components, the way that check components are indicated on-screen depend on the window manager or operating system being used. A tick to the left of any items which are "switched on" is typical. Alternatively, a square button to the left of check component items (depressed for items which are on) may be used.

Common LispWorks User Guide, Liquid Common Lisp Version 5.0 - 18 OCT 1996

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