I finally tracked down why the gutter is flashing all the time when
using Gnus. The problem is that the Gnus mime code is full of
(save-current-window
(select-window w)
...))
and
(save-window-excursion
(select-window w)
..))
and these select-window's call record-buffer-hook which does the
update tab stuff.
This
a. is unnecessary work (but that is probably a gnus problem).
b. The gutter is redisplaying too soon. If it just waited until the
save-window-excursiom is finished (like the rest of the redisplay
does) there would not be any visible effect.
Jan
P.S. I don't know why the mime code is doing this.