anchor.diff:                                           0
                                            (round x1))
                                   0)))
  -          (when (> y2 (+ y-position viewport-height))
  +          (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)))))))
  
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:           (x2 dimensions) (+ x1 line-width)
            (y2 dimensions) (+ y1 line-height))))
  
  (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'."
    (end-line line line-x1 line-y1 line-width line-height)
    (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)
  