GNU bug report logs - #69941
30.0.50; Faulty fontification of radio button widgets

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Message #95 received at 69941 <at> debbugs.gnu.org (full text, mbox):

From: Mauro Aranda <maurooaranda <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 69941 <at> debbugs.gnu.org, Stephen Berman <stephen.berman <at> gmx.net>,
 Eli Zaretskii <eliz <at> gnu.org>
Subject: Re: bug#69941: 30.0.50; Faulty fontification of radio button widgets
Date: Fri, 17 Jan 2025 08:52:29 -0300

[Message part 1 (text/plain, inline)]

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

>> I attach a patch with a first idea (based on Stefan's suggestions),
>> where we "protect" the parent's markers, inside widget-default-create.
>> This is so we can try to catch almost all situations where this bug
>> might arise.
>
> I can't judge whether `widget-default-create` covers all the cases, but
> other than that, it's looking good (well, I find this "set and later 
reset"
> to be rather ugly/brittle, but that's probably as good as it gets given
> what we have).

Thanks for taking a look.

>> +(defun widget--protect-parent-markers (widget)
>> +  "Protect the :from and :to markers of the WIDGET's parent, if 
necessary.
>> +
>> +Usually, the :from marker has type t, while the :to marker has type 
nil.
>> +When creating a child or a button inside a composite widget, they 
have to be
>> +changed to nil and t respectively, so that the WIDGET's parent (if 
any),
>> +properly contains all of its children and buttons."
>> +  (let* ((parent (widget-get widget :parent))
>> +         (parent-from-marker (and parent (widget-get parent :from)))
>> +         (parent-to-marker (and parent (widget-get parent :to)))
>> +         (pos (point)))
>> +    (when (and parent-from-marker
>> +               (eq pos (marker-position parent-from-marker)))
>> +      (set-marker-insertion-type parent-from-marker nil))
>> +    (when (and parent-to-marker
>> +               (eq pos (marker-position parent-to-marker)))
>> +      (set-marker-insertion-type parent-to-marker t))))
>> +
>> +(defun widget--unprotect-parent-markers (widget)
>> +  "Unprotect the :from and :to markers of the WIDGET's parent, if 
necessary.
>> +
>> +Changes the :from marker type back to t and the :to marker type 
back to nil."
>> +  (let* ((parent (widget-get widget :parent))
>> +         (parent-from-marker (and parent (widget-get parent :from)))
>> +         (parent-to-marker (and parent (widget-get parent :to))))
>> +    (when parent-from-marker
>> +      (set-marker-insertion-type parent-from-marker t))
>> +    (when parent-to-marker
>> +      (set-marker-insertion-type parent-to-marker nil))))
>
> I'm not a big fan of the name "protect" here, to be honest.
> Maybe `widget--prepare-parent-for-insertion`?

Sounds a little bit better, thanks.  I went for something similar.

>> It doesn't catch _all_, in theory, since it might happen
>> that a grandparent widget doesn't adjust its markers, but maybe that's
>> unusual enough that we can get away with it.
>
> We can probably handle that case easily by just adding to
> `widget--protect-parent-markers` a recursive call if either the :from or
> the :to marker had to be adjusted.  The only difficulty I see is making
> sure we adjust all the makers in the "unprotect" case that we
> protected earlier.  Maybe we should make
> `widget--protect-parent-markers` return a list of (MARKER
> . PREVIOUS-TYPE) so the `widget--unprotect-parent-markers`
> would turn into something like (mapcar (apply-partially #'apply
> #'set-marker-insertion-type) ...).
> IIUC that list would be empty in the vast majority of cases.

Thanks for this idea.

I attach a patch that implements something like that, along with a new
test to check the recursive case.

[0001-Prepare-markers-for-insertions-inside-of-a-widget.patch (text/x-patch, attachment)]

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