customize-face

[martin rudalics]

Suppose my .emacs is

(custom-set-faces
  ;; custom-set-faces was added by Custom.
  ;; If you edit it by hand, you could mess it up, so be careful.
  ;; Your init file should contain only one such instance.
  ;; If there is more than one, they won't work right.
 '(isearch ((((class color) (min-colors 88) (background light))
             (:background "magenta" :foreground "lightskyblue1")))))

and I do

M-x customize-face RET isearch RET

and try to reinsert "3" after "magenta" I get

Debugger entered--Lisp error: (error "Change in different fields")
  signal(error ("Change in different fields"))
  error("Change in different fields")
  widget-after-change(1090 1143 0)