checkbox WidgetSyntax:
type ::= (checkbox [keyword argument]...)
A widget to represent a toggle widget, with a checkbox. Its super is
the toggle widget.
This widget has two possible states, ‘selected’ and
‘unselected’, which corresponds to a t or nil
value, respectively.
It either overrides or adds the following properties:
:button-prefixThe empty string.
:button-suffixThe empty string.
:formatBy default, buttonizes the value.
:onBy default, the string “[X]”.
:offBy default, the string “[ ]”.
:on-glyphThe name of the image to use when the state is ‘on’.
:off-glyphThe name of the image to use when the state is ‘off’.
:actionA function that toggles the checkbox, notifies the parents and in the ‘on’ state, activates its siblings.