Asynchronous error with w3m image display

[Uday Reddy]

Robert Marsall reports (6/16/2010):

I'm using w3m to display images with vm 8.1.90a and find that *sometimes*
if I move to another message before w3m has finished retrieving and
displaying images I get lots of errors (and beeps!)
error in process sentinel: Args out of range: 1, 1

e.g.(traceback is hard to get as the minibuffer line gets taken over
with the repetition of these messages)

Debugger entered--Lisp error: (args-out-of-range 1 1)
  get-text-property(#<marker at 1 in INBOX Presentation> face)
  w3m-insert-image(#<marker at 1 in INBOX Presentation> #<marker at 1 in INBOX Presentation>
  (image :type gif :data "GIF89a..." :ascent center :background nil)
  "http://newsletter.gramophone.net/files/.../images/spacer.gif")

ellipses added by me in the above!

partially this is w3ms problem but I guess vm should, when you move
messages, be stopping any w3m sub-processes?