bug#10539: 24.0.92; low display-time-interval makes Emacs slow

[martin rudalics]

> Would the following wording make it less confusing/contradictory?
>
>   Force next redisplay cycle to update the current buffer's mode line

A buffer doesn't have a mode or header line.  And a body like

  (if all (with-current-buffer (other-buffer)))
  (set-buffer-modified-p (buffer-modified-p)))

indicates that this function exclusively relies on obscure side effects
which are not documented anywhere.

martin