Strange Code

(defface w3m-history-current-url
  ;; The following strange code compounds the attributes of the
  ;; `secondary-selection' face and the `w3m-arrived-anchor' face,
  ;; and generates the new attributes for this face.
  (let ((base 'secondary-selection)
        (fn (if (featurep 'xemacs)
              'custom-face-attributes-get));; What a perverseness it is.
        ;; Both `face-custom-attributes-get' in XEmacs and
        ;; `custom-face-attributes-get' in CUSTOM 1.9962 attempt to
        ;; require `font' in Emacs/w3 and `cl' arbitrarily. :-/
        (features (cons 'font features))
        base-attributes attributes attribute)
    (setq base-attributes (funcall fn base nil)
          attributes (funcall fn 'w3m-arrived-anchor nil))
    (while base-attributes
      (setq attribute (car base-attributes))
      (unless (memq attribute '(:foreground :underline))
        (setq attributes (plist-put attributes attribute
                                    (cadr base-attributes))))
      (setq base-attributes (cddr base-attributes)))
    (list (list t attributes)))
  "Face used to highlight the current url in the \"about://history/\" page."
  :group 'w3m-face)

These days one would simply use :inherit for both w3m-arrived-anchor and secondary-selection.