highlighting non-ASCII characters (was: Translation of http status code to text)

[Ted Zlatanov]

On Tue, 23 Mar 2010 11:55:17 +0200 Juri Linkov <address@hidden> wrote: 

>> Thanks for noticing that.  I had the cyrillic-translit input method on
>> accidentally.  It would be nice if I could highlight non-ASCII
>> characters in a subtle way to avoid this, is there a relevant face?

JL> Maybe `escape-glyph' is a relevant face?

I don't think it applies to non-ASCII by default, at least for me it
doesn't.  I can set up font-lock for myself, of course, but was
wondering if Emacs has a simple built-in way to highlight them.

Also it would be good if the effect did not interfere with other faces,
so e.g. a subtle fading or underline effect overlaid with the regular
face would be nicer than just asking the user to customize it themselves
(although that option is still valuable).  I don't know much about Emacs
faces so any help is welcome.

Ted