bug#16177: 24.3.50; Display glyphs for hard spaces in color

[Sebastien Vauban]

Hello,

In French, you have a narrow nobreak space (202F) in front of the colon : « as
well between quotes »...

Before "high punctuation symbols" (such as ! and ?), it is a "common" nbsp
(00A0): Hello ! How are you ?

Problem #1:

To get hard spaces (aka nbsp) highlighted, you need to add `spaces' to
`whitespace-style':

#+begin_src emacs-lisp
  ;; which kind of blank is visualized
  (setq whitespace-style
        '(face trailing tabs spaces
          indentation::space space-mark tab-mark))
#+end_src

Doing so, all the normal spaces are highlighted as well...

And setting the background of `whitespace-space' to `white' is not a solution,
as Org headings would become weird (when they use a background color).

Problem #2:

Narrow nbsp aren't highlighted.

See http://screencast.com/t/3qtxb3vTxcS for visualizing both problems.

Best regards,
  Seb