emacs -Q
In *scratch* buffer eval this:
(setq whitespace-style '(lines-tail))
(whitespace-mode)
Now type a line of text with mode than 80 characteres.
Until recently, the characters after the 80th column were highlighted
with a prominent background color, which is the documented behavior.
In GNU Emacs 24.0.50.1 (x86_64-unknown-linux-gnu, X toolkit)
of 2010-09-16 on qcore
Windowing system distributor `The X.Org Foundation', version 11.0.10706000
configured using `configure '--without-toolkit-scroll-bars'
'--with-x-toolkit=lucid''
Important settings:
value of $LC_ALL: nil
value of $LC_COLLATE: nil
value of $LC_CTYPE: nil
value of $LC_MESSAGES: nil
value of $LC_MONETARY: nil
value of $LC_NUMERIC: nil
value of $LC_TIME: nil
value of $LANG: en_US.UTF-8
value of $XMODIFIERS: nil
locale-coding-system: utf-8-unix
default enable-multibyte-characters: t