anchor.diff:     initargs :child :children))
   
   
  -(defmethod create-callback-function ((container container) function arg1)
  -  (if (eq arg1 :children)
  +(defmethod compute-signal-function ((container container) signal function object)
  +  (if (eq object :children)
         #'(lambda (&rest args)
   	  (mapc #'(lambda (child)
   		    (apply function child (rest args)))
  
positive.code:       #'make-instance
        (gethash (class-of container) *container-to-child-class-mappings*)
        :parent container :child widget args))))
  
  
  (defbinding %container-remove () nil
    (container container)
  
negative.code:   (if (null focusable-widgets)
        (%container-unset-focus-chain container)
      (%container-set-focus-chain container focusable-widgets)))
  
  (defgeneric container-show-recursive (container))
  
  (defmethod container-show-recursive ((container container))
    "Recursively shows any child widgets except widgets explicit hidden during construction."
    (labels ((recursive-show (widget)
  	     (when (typep widget 'container)
  	       (if (not (user-data-p widget 'show-recursive-p))
  		   (container-foreach widget #'recursive-show)
  		 (unset-user-data widget 'show-recursive-p)))
  	     (unless (widget-hidden-p widget)
  	       (widget-show widget))))
      (container-foreach container #'recursive-show)))
  