Re: Making a non-ASCII space character visible

[Will Parsons <varro@nodomain.invalid>]

On Sunday, 17 Jun 2018  2:00 AM -0400, Eli Zaretskii wrote:
>> From: Will Parsons <varro@nodomain.invalid>
>> Date: Sat, 16 Jun 2018 16:15:59 -0400
>> 
>> I have a desire to use the Unicode character A007 (FIGURE SPACE) in a
>> document and to be able to distinguish it visually from a regular ASCII
>> space.  This seems to be already done in the case of 00A0 (NO-BREAK
>> SPACE) which appears as an underscore with a distinctive face.
>> 
>> It *looks* like I should be able to do this via the customization
>> option "Whitespace Display Mappings", but no matter what I do,
>> attempting to "Apply" the changes results in an error message, "This
>> field should contain a single character".  (This message occurs even
>> if I try to change one of the display characters of an existing entry
>> in the list and apply.)
>
> Whitespace Display Mappings only has effect if you turn on
> whitespace-mode.  The special display of u+00A0 does not require
> whitespace-mode, it is implemented directly in the display engine.
> Maybe we should extend that built-in treatment to the other
> "space-like" characters.

OK - that explains the difference I see between the display of u+00A0
and u+2007, but now I'm even more confused about activating
whitespace-mode:

What I have had in my .emacs file for years is the following:

  (global-whitespace-mode 1)
  (setq-default whitespace-style '(face lines-tail tabs trailing))

Examining the value of whitespace-mode shows nil, however.

Adding (whitespace-mode 1) to my .emacs file apparently has no effect;
the value of whitespace-mode is still nil.

Now if I interactively run the command "whitespace-mode", the value of
the variable whitespace-mode turns to t, but the display of u+2007
remains unchanged.

>> Feeling desperate, I copied the existing value of
>> whitespace-display-mappings directly into my custom.el file, and
>> manually added a new entry for A007 (8199) on the model of the
>> existing entry for 00A0 (160), but this seems to have no effect on the
>> display.
>
> Did you also turn on whitespace-mode?

See above.

-- 
Will