documentation-string WidgetSyntax:
type ::= (documentation-string [keyword argument]... value)
A widget to represent a documentation string. Its super is the
item widget.
It either overrides or adds the following properties:
:formatBy default, insert its value.
:value-createFunction to insert a documentation string, possibly hiding part of the documentation if its large.
To show or hide the rest of the documentation, uses a
visibility widget.
:actionFunction to toggle showing the documentation upon an event.
:visibility-widgetA symbol, the type of the widget to use for the visibility widget.
This is, by default, the symbol visibility.