anchor.diff:                                    tree))))))
            (insert-content (ps:ps (setf (ps:@ document Body |innerHTML|)
                                         (ps:lisp content)))))
  +    (print content)
       (ffi-buffer-evaluate-javascript-async output-buffer insert-content)
       (set-current-buffer output-buffer)))
   
  
positive.code:     (ffi-buffer-evaluate-javascript-async output-buffer insert-content)
      (set-current-buffer output-buffer)))
  
  (define-command history-tree ()
    "Open a new buffer displaying the whole history tree."
    (let* ((buffer-name (format nil "*History*"))
           (output-buffer (or (find-if (lambda (b) (string= buffer-name (title b)))
                                       (buffer-list))
                              (nyxt/help-mode:help-mode
  
negative.code:          (tree `(:ul ,(htree:map-tree
                         #'(lambda (node)
                             `(:li (:a :href ,(object-string (url (htree:data node)))
                                       ,(integer->unicode-geometric (id (htree:data node)))
                                       ,(let ((title (or (match (title (htree:data node))
                                                           ((guard e (not (str:emptyp e))) e))
                                                         (object-display (url (htree:data node))))))
                                          (if (eq node (htree:current history))
                                              `(:b ,title)
                                              title)))))
                         (htree:root history)
                         :include-root t
                         :collect-function #'(lambda (a b) `(,@a ,(when b `(:ul ,@b)))))))
           (tree-style
             (cl-css:css
              '((body
                 :line-height "initial")
                (* :margin 0
                   :padding 0
                   :list-style "none")
                ("ul li"
                 :margin-left "15px"
                 :position "relative"
                 :padding-left "5px")
                ("ul li::before"
                 :content "' '"
                 :position "absolute"
                 :width "1px"
                 :background-color "#000"
                 :top "5px"
                 :bottom "-12px"
                 :left "-10px")
                ("body > ul > li:first-child::before"
                 :top "12px")
                ("ul li:not(:first-child):last-child::before"
                 :display "none")
                ("ul li:only-child::before"
                 :display "list-item"
                 :content "' '"
                 :position "absolute"
                 :width "1px"
                 :background-color "#000"
                 :top "5px"
                 :bottom "7px"
                 :height "7px"
                 :left "-10px")
                ("ul li::after"
                 :content "' '"
                 :position "absolute"
                 :left "-10px"
                 :width "10px"
                 :height "1px"
                 :background-color "#000"
                 :top "12px"))))
           (content (markup:markup
                     (:body (:h1 "History")
                            (:style (style output-buffer))
  