Eli Zaretskii writes:
>> >> I can't really reproduce the line-move error either in this mode. It
>> >> does show up occasionally but I haven't figured out how to
>> >> explicitly trigger it thus far.
>> >
>> > I'll try reproducing it here.
>> 
>> I also tried the patch on current trunk. I use the following snippet to
>> generate a buffer containing large and small images as well as text:
>
> Thanks.  Unfortunately, using Emacs with Imagemagick support is a
> no-starter for me.

It's only needed for scaling, though. If you have at least libjpeg, then
just download those two images

http://randomsample.de/bigimage.jpg
http://randomsample.de/smallimage.jpg

and use

(with-current-buffer (get-buffer-create "test")
  (erase-buffer)
  (let ((imagelarge (create-image "~/bigimage.jpg"))
	(imagesmall (create-image "~/smallimage.jpg")))
    (dotimes (i 20)
      (insert "\n*** " (number-to-string i)" ***\nThis is a line of text.\nAnd here's a large image:\n")
      (insert-image imagelarge)
      (insert "\nAnd a small image:\n")
      (insert-image imagesmall))
    (goto-char (point-min))))

>However, I tried to cover every possibility of using non-numeric values
>in numeric context.  Please try the patch below (it's relative to the
>current trunk, not to the previous patch), and see if it gives good
>results.  If you still get errors, please manually load simple.el (not
>simple.elc) into your Emacs, run your test snippet, and see if the
>backtrace can pinpoint the place where I missed something.

It fails in line 4789 because 'py' is nil. I attached the backtrace.

-David