> I agree that the buffer list is more global than a window, but OTOH
 > it makes sense to use buffer-local hook for a buffer to get notified
 > when it comes to the top of the buffer list.  So this would be a good thing
 > to have, unless there is another hook that gets called when a buffer
 > becomes the current buffer, or at least displayed in a window.

I try to fix the problem you mentioned earlier, namely that

 > > it's called only when navigating away from the
 > > image-mode buffer, but not when coming back to the image-mode buffer, e.g.
 > > `C-x <left>', then resize the window, then type `C-x <right>',
 > > it's not called.  Also it's not called in another direction:
 > > `C-x <right>', then resize the window, then type `C-x <left>'.

Please tell me if the attached patch works and what else should be
done.

Thanks, martin