anchor.diff:                        :documentation "If non-nil, input is replaced by
   placeholder character.  This is useful to conceal passwords.")
      (completions :accessor completions :initform nil)
  +   (completion-head :accessor completion-head :initform 0)
      (completion-cursor :accessor completion-cursor :initform 0)
      (content :accessor content :initform ""
               :documentation "The HTML content of the minibuffer.")
  
positive.code:          (:body
            (:div :id "container"
                  (:div :id "input" (:span :id "prompt" "") (:span :id "input-buffer" ""))
                  (:div :id "completions" ""))))))
  
  (defmethod evaluate-script ((minibuffer minibuffer) script) ; TODO: Rename function?  `set-content'?  Or `defmethod (setf content)' instead?  If we do, then `show' does not need to call anything like `evaluate-script' or `show'.  Question: Do we need to "stack" content parts before updating it?  We can do both: Have evaluate-script that takes a parenscript, and (setf content) that takes an HTML string.
    "Evaluate SCRIPT into MINIBUFFER's webview.
  
negative.code:                                   ;; content) (html (minibuffer minibuffer))),
                                    ;; there'd be no need for this measure, at the
                                    ;; cost of more Javascript evaluations.
                                    ;; (ps:ps (ps:chain document
                                    ;;                  (write (ps:lisp (content minibuffer)))))
                                    script
                                    ;; Return the new HTML body.
                                    (ps:ps (ps:chain document body |outerHTML|)))))
  