bug#39360: Add :extend attribute to show-paren-mode expression face

[Clément Pit-Claudel]

On 2020-01-31 12:22, Eli Zaretskii wrote:
>> Date: Fri, 31 Jan 2020 19:12:19 +0200
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 39360@debbugs.gnu.org
>>
>>> Cc: 39360@debbugs.gnu.org
>>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>>> Date: Fri, 31 Jan 2020 11:12:37 -0500
>>>
>>> I couldn't find a program on my machine that behave like Emacs now does 
>>> (highlighting explicit newlines).
>>
>> MS Office does.
> 
> Also, most text buffers in Emacs have explicit newlines at the end of
> each line, so highlighting them is more like LibreOffice and Firefox
> do.

As far as I can tell, Firefox highlights a space at the end of the line only if 
there is an actual space (ascii 32), but not if there's an explicit newline.  
In other words, it highlights over continuation lines, but not over explicit 
newlines.

That is to say, we highlight this (with show-paren-mode and visual-line-mode, 
assuming the line is too long to fit in the window):

(test test test test test test test test test test test test test test test 
test test test test test test test test test test)

the same way as this:

(test test test test test test test test test test test test test test test
test test test test test test test test test test)

Whereas firefox highlights the end-of-line blank only in the first case, right 
where the line wraps.

Clément.