Subject: bug#64166: 29.0.92; A :box with negative vertical width does not avoid any increase in the line height

From: Sebastian Miele <[email-masked]>
Date: Tue, 20 Jun 2023 18:12:25 +0200

Eli Zaretskii <[email-masked]> writes:

>> At the end of the second line, evaluate (‘eval-expression’):
>> 
>>   (insert (propertize "text" 'face '(:box '(:line-width (-1 . -1)))))
>> 
>> The height of the line clearly changes.  But that is contrary to what
>> the manual says about the ‘:box’ face attribute:
>> 
>>   "A negative horizontal or vertical width −N means to draw a line of
>>   width N that occupies the space of the underlying text, thus avoiding
>>   any increase in the character height or width."
>
> The above is incorrect face specification.  Try this instead:
>
>   (insert (propertize "text" 'face '(:box (:line-width (-1 . -1)))))
>
>> Apart from that:
>> 
>> (1) Using ‘:line-width (-1 . -1)’ seems to yield the exact same result
>> as ‘:line-width (1 . 1)’ does, both in width and in height.
>> 
>> (2) Using even larger negative values has no effect.
>> ‘:line-width (-10 . -10)’ also seems to yield the exact same result as
>> ‘:line-width (1 . 1)’ does.
>> 
>> Apparantly, all negative values are treates as positive 1, contrary to
>> what the manual states.
>
> What happens if you remove the redundant quote?

Everything works as expected.  Sorry for the noise.

All the best!