region-to-frame.el

(defun region-to-frame ()
  (interactive)
  (unless (region-active-p)
    (error "No region active."))
  (let* ((start (region-beginning))
         (end (region-end))
         (start-line (save-excursion (line-number-at-pos start)))
         (start-column (save-excursion (goto-char start) (current-column)))
         (start-string (if (< 0 start-column)
                           (format "+%s:%s" start-line start-column)
                         (format "+%s"start-line)))
         (end-line (save-excursion (line-number-at-pos end)))
         (end-column (save-excursion (goto-char end) (current-column)))
         (end-string (if (< 0 end-column)
                         (format "+%s:%s" end-line end-column)
                       (format "+%s" end-line)))
         (new-buffer (make-indirect-buffer (current-buffer)
                                           (generate-new-buffer-name (format "*Fragment %s%s%s*"
                                                                             (buffer-name (current-buffer))
                                                                             start-string
                                                                             end-string))
                                           t)))
    (with-current-buffer new-buffer
      (narrow-to-region start end)
      (let ((frame-height 1)
            (frame-width 0))
        (save-excursion
          (goto-char (point-max))
          (while (< (point-min) (point))
            (forward-line -1)
            (incf frame-height)
            (setf frame-width (max frame-width (- (line-end-position) (line-beginning-position))))))
        (let ((frame (new-frame (list (cons 'width frame-width)
                                      (cons 'height (+ 2 frame-height))
                                      (cons 'minibuffer t)))))
          (select-frame frame)
          (when (region-active-p)
            (deactivate-mark)))))))

(provide 'region-to-frame)