anchor.diff:            (x2 dimensions) (+ x1 line-width)
             (y2 dimensions) (+ y1 line-height))))
   
  -(defun end-line-cleaning-up (view pane line line-x1 line-y1
  +(defun end-line-cleaning-up (view line line-x1 line-y1
                                line-width line-height)
     "End the addition of strokes to `line' for now, and update the
  -dimensions of `line'. Update all undisplayed lines to have no
  -associated dimensions. Also clear from the bottom of strokes to
  -the bottom of the line, and from the end of the line to the end
  -of the sheet."
  +dimensions of `line'."
     (end-line line line-x1 line-y1 line-width line-height)
  -  (with-accessors ((line-x1 x1) (line-y1 y1)
  -                   (line-x2 x2) (line-y2 y2)) (line-dimensions line)
  -    (setf (max-line-width view)
  -          (max (max-line-width view)
  -               (dimensions-width (line-dimensions line))))
  -    ;; If a has a lesser height than the line, clear from the top of
  -    ;; the line stroke to the top of the stroke, to avoid artifacts
  -    ;; left over from previous redisplays.
  -    (do-displayed-line-strokes (stroke line)
  -      (let ((stroke-dimensions (stroke-dimensions stroke)))
  -        (with-accessors ((stroke-x1 x1) (stroke-y1 y1)
  -                         (stroke-x2 x2) (stroke-y2 y2)) stroke-dimensions
  -          (when (> line-height (dimensions-height stroke-dimensions))
  -            (clear-rectangle* pane stroke-x1 line-y1
  -                              stroke-x2 stroke-y1)))))
  -    ;; Reset the dimensions of undisplayed lines.
  -    (do-undisplayed-line-strokes (stroke line)
  -      (let ((stroke-dimensions (stroke-dimensions stroke)))
  -        (with-accessors ((stroke-x1 x1) (stroke-y1 y1)
  -                         (stroke-x2 x2) (stroke-y2 y2)) stroke-dimensions
  -          (setf stroke-x1 0 stroke-y1 0
  -                stroke-x2 0 stroke-y2 0))))))
  +  (setf (max-line-width view)
  +        (max (max-line-width view)
  +             (dimensions-width (line-dimensions line)))))
   
   (defun draw-line-strokes (pane view initial-pump-state
                             start-offset cursor-x cursor-y)
  
positive.code: anything. Will use the function specified in the drawing-options
  of `stroke' to carry out the actual calculations."
    (unless (and (= cursor-x (x1 (stroke-dimensions stroke)))
                 (not (stroke-dirty stroke)))
      (invalidate-stroke stroke :modified t))
    (when (stroke-dirty stroke)
      (funcall (drawing-options-function (stroke-drawing-options stroke)) stream view stroke
  
negative.code:                                          0
                                           (round x1))
                                  0)))
            (when (and (> y2 (+ y-position viewport-height))
                       (not (end-of-buffer-p (bot view))))
              (full-redisplay pane)
              ;; We start all over!
              (display-drei-pane (pane-frame pane) pane)))))))
  