On 11/30/2012 01:53 PM, Eli Zaretskii wrote:

> OK.  So what do you suggest, in practical terms?  Are you saying that
> we should use BUF_MODIFF(XBUFFER (w->buffer)) instead of MODIFF and
> BUF_OVERLAY_MODIFF(XBUFFER (w->buffer)) instead of OVERLAY_MODIFF
> inside window_outdated?  Or do you suggest something else?
>
> I'm okay with using BUF_* macros in window_outdated.

There is one more similar thing: if we can enter redisplay_internal
with different current_buffer and selected window's buffer, we can
confuse reconsider_clip_changes, which comment explicitly assumes
that W->buffer and B are the same buffer.

What if we just delay the real redisplay action until current_buffer
and selected window's buffer becomes synchronized, assuming that it
happens in the very near future (when someone finally update current_buffer
with selected window's buffer and then attract redisplay attention with
++windows_or_buffers_changed or similar)?

> So if window_outdated is called not from redisplay_window or its
> subroutines, we cannot assume that current_buffer and the selected
> window's buffer are the same.  Also, for minibuffer windows and
> pseudo-windows, we may need more care, but I'm not sure.

IIUC pseudo-windows are always non-leaf; so, selected_window can't be
a pseudo-window, and pseudo-window can't be passed to redisplay_window.

Attached patch illustrates all from the above.

Dmitry