anchor.diff:      with quote."
     (concat-str "'" str "'"))
   
  -(defun secho-arg (str)
  -  " An argument for echo command of screeen must be wrapped
  -    with double quote."
  +(defun sstringarg (str)
  +  " A string arguments for screen command must be double quoted."
     (concat-str "\"" str "\""))
   
   (defun state-leave-desc (state)
  
positive.code: ; a form generates the message
  (keybind-common l snormal snormal ((focus right)) (coerce (coerce "focus right" 'list) 'string))
  (keybind-common l snormal snormal ((focus right)) "")
  
  (defun normalize-cmd-format (cmd)
    (cond ((null cmd) '())
  
negative.code:   `(keybind ,key ,start ,dst
              ,commands
              (,(cond ((null message)
                       `(hardstatus string
                                    (:lisp (sstringarg (default-message
                                                        ',dst
                                                        ,(com-stringify-form (car commands)))))))
                      ((zerop (length message)) ())
                      (t `(hardstatus string (:lisp (sstringarg ,message))))))))
  
  (keybind-common j snormal snormal ((focus down)))
  (keybind-common k screen raw ((focus up)) "focus up")
  