anchor.diff:  
   
   (defun display-backtrace (frame pane)
  -  (declare (ignore frame)) 
  +  (declare (ignore frame))
     (with-text-family (pane :sans-serif)
       (bold (pane) (format pane "Backtrace:")))
     (fresh-line pane)
  
positive.code: (defun simple-break ()
    (with-simple-restart  (continue "Continue from interrupt.")
      (with-debugger
        (invoke-debugger 
         (make-condition 'simple-error 
                         :format-control "Debugger test")))))
  
  
negative.code: ;;; This is the beginning of a Common Lisp debugger implemented in
  ;;; McCLIM. It uses the portable debugger interface developed for the
  ;;; Slime project, and the graphical layout is also heavily inspired
  