variable-link WidgetSyntax:
type ::= (variable-link [keyword argument]... var)
A widget to represent a link to an Emacs variable. Its super is the
link widget.
It overrides the :action property, to a function to describe
var.
Example:
(widget-create 'variable-link
:button-prefix ""
:button-suffix ""
:tag "What setting controls button-prefix?"
'widget-button-prefix)