My button has disappeared (well, turned black) :O
The apply class exists in both of the trees, is it expected to be
disregarded now?
<!DOCTYPE html>
<html><head><style>
body
{
background: black;
}
.apply [stroke="black"]
{
fill: #ffffff;
stroke: #ffffff;
}
</style>
</head><body>
<div>
<svg width="90vw" height="90vh" viewBox="0 0 50 50" class="apply">
<symbol id="svg-pause" viewBox="0 0 50 50">
<rect x="5" y="5" width="15" height="40" stroke="black"></rect>
<rect x="30" y="5" width="15" height="40" stroke="black"></rect>
</symbol>
<a href="#">
<use href="#svg-pause" x="20" y="37" width="10" height="11"></use>
</a>
</svg>
</div>
</body></html>
☆*PhistucK*
On Wed, Nov 12, 2025 at 5:11 PM Daniel Bratell <[email protected]> wrote:
> LGTM3 - Risk seems manageable even though it's unfortunately hard to
> measure. That it has worked for such a long time in Gecko without major
> push towards something else is a good sign. Good luck. We're all counting
> on you.
>
> /Daniel
>
> On 2025-11-12 10:32, Mike Taylor wrote:
>
> On 11/10/25 7:22 p.m., Rune Lillesveen wrote:
>
> On Sat, Nov 8, 2025 at 12:59 AM Rick Byers <[email protected]> wrote:
>
>> This has some risk of being a breaking change, right? How would
>> you characterize that risk? Firefox having this is obviously a good sign,
>> but any other data or arguments on the risk? I imagine SVG use is fairly
>> rare, and any selector mismatch would most likely be a minor formatting
>> issue, right?
>>
> That, or some display:none rule that didn't work before, starts working
> now, which could be a major or minor issue.
>
>
> An instantiated subtree will no longer be able to do selector matching
> against the surrounding elements from where it was instantiated from.
>
> In the following case, the use instance of the rect would no longer be red:
>
> <!DOCTYPE html>
> <style>
> .original rect { fill: red; }
> rect { fill: green; }
> </style>
> <svg>
> <defs class="original">
> <rect id="r" x="0" y="0" width="100" height="100" />
> </defs>
> <use href="#r"></use>
> </svg>
>
> I think this is unlikely to break real sites.
>
> I spent some time poking through the Firefox bug and its various
> associated bugs. I think it's a pretty good sign that this landed 8 years
> ago and the reported regressions were due to implementation bugs that were
> quickly fixed.
>
> The absence of bugs in Bugzilla isn't a perfect compat signal, but it's at
> least promising.
>
> In order to use-count this, we would have to run both ways of cascading
> (or at least selector matching) to detect such cases.
>
> This sounds like a lot of complexity (but feel free to respond telling me
> it's trivial to implement). So, LGTM2 and hopefully I'm not wrong about the
> risk here.
>
>
> The main benefit from this change, I think, is that it fixes
> https://crbug.com/40663285 which is about :hover and other state selector
> matching which is currently broken in <use> instances.
>
> On Fri, Nov 7, 2025 at 1:51 AM Philip Jägenstedt <[email protected]>
>> wrote:
>>
>>> LGTM1
>>>
>>> The WebKit standards position was only filed yesterday, but this seems
>>> straightforward and aligns with spec+Firefox, so I don't think we should
>>> wait on it. In the unlikely event there is feedback, please ping this
>>> thread.
>>>
>>> On Fri, Nov 7, 2025 at 9:44 AM Rune Lillesveen <[email protected]>
>>> wrote:
>>>
>>>> *Contact emails*
>>>> [email protected]
>>>>
>>>> *Specification*
>>>> https://www.w3.org/TR/SVG2/struct.html#UseElement
>>>>
>>>> *Summary*
>>>> Align the Blink implementation with the SVG2 specification for matching
>>>> CSS rules in <use> element trees.
>>>>
>>>> Match selectors against the <use> instantiation elements instead of the
>>>> originating element subtree. This means selectors will no longer match
>>>> ancestor and sibling elements outside the cloned subtree. More importantly,
>>>> state selectors like :hover will now start matching in <use> instances.
>>>>
>>>> *Blink component*
>>>> Blink>SVG
>>>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ESVG%22>
>>>>
>>>> *Web Feature ID*
>>>> Missing feature
>>>>
>>>> *Motivation*
>>>> CSS selectors match against the wrong tree for <use> instantiations,
>>>> which means selectors do not match correctly for structural relationships
>>>> and user interaction state (see :hover issue that will be fixed shipping
>>>> this feature: https://crbug.com/40663285)
>>>>
>>>> *Initial public proposal*
>>>> *No information provided*
>>>>
>>>> *TAG review*
>>>> *No information provided*
>>>>
>>>> *TAG review status*
>>>> Not applicable
>>>>
>>>> *Risks*
>>>>
>>>>
>>>> *Interoperability and Compatibility*
>>>> Firefox has shipped the SVG2 behavior for years. Bug for WebKit:
>>>> https://bugs.webkit.org/show_bug.cgi?id=249080
>>>>
>>>> *Gecko*: Shipped/Shipping (
>>>> https://bugzilla.mozilla.org/show_bug.cgi?id=265894#c190) Shipped in
>>>> Firefox 56
>>>>
>>>> *WebKit*: No signal (
>>>> https://github.com/WebKit/standards-positions/issues/571)
>>>>
>>>> *Web developers*: Positive 44 votes on the crbug issue, and additional
>>>> 5 votes on the :hover bug https://crbug.com/40663285
>>>>
>>>> *Other signals*:
>>>>
>>>> *WebView application risks*
>>>>
>>>> Does this intent deprecate or change behavior of existing APIs, such
>>>> that it has potentially high risk for Android WebView-based applications?
>>>> *No information provided*
>>>>
>>>>
>>>> *Debuggability*
>>>> *No information provided*
>>>>
>>>> *Will this feature be supported on all six Blink platforms (Windows,
>>>> Mac, Linux, ChromeOS, Android, and Android WebView)?*
>>>> Yes
>>>>
>>>> *Is this feature fully tested by web-platform-tests
>>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
>>>> Yes
>>>>
>>>> https://wpt.fyi/svg/linking/reftests/use-descendant-combinator-003.html
>>>> https://wpt.fyi/svg/struct/reftests/use-inheritance-001.svg
>>>> https://wpt.fyi/svg/struct/reftests/use-inheritance-nth-child-of.svg
>>>>
>>>> https://wpt.fyi/svg/struct/reftests/use-inheritance-nth-last-child-of.svg
>>>>
>>>> https://wpt.fyi/svg/styling/use-element-attr-selector-transition.tentative.html
>>>>
>>>> https://wpt.fyi/svg/styling/use-element-id-selector-transition.tentative.html
>>>>
>>>> *Flag name on about://flags*
>>>> #enable-experimental-web-platform-features
>>>>
>>>> *Finch feature name*
>>>> Svg2Cascade
>>>>
>>>> *Rollout plan*
>>>> Will ship enabled for all users
>>>>
>>>> *Requires code in //chrome?*
>>>> False
>>>>
>>>> *Tracking bug*
>>>> https://crbug.com/40550039
>>>>
>>>> *Estimated milestones*
>>>> Shipping on desktop 144
>>>> Shipping on Android 144
>>>> Shipping on WebView 144
>>>>
>>>> *Anticipated spec changes*
>>>>
>>>> Open questions about a feature may be a source of future web compat or
>>>> interop issues. Please list open issues (e.g. links to known github issues
>>>> in the project for the feature specification) whose resolution may
>>>> introduce web compat/interop risk (e.g., changing to naming or structure of
>>>> the API in a non-backward-compatible way).
>>>> *No information provided*
>>>>
>>>> *Link to entry on the Chrome Platform Status*
>>>> https://chromestatus.com/feature/5134266027606016?gate=6607474169872384
>>>>
>>>> This intent message was generated by Chrome Platform Status
>>>> <https://chromestatus.com/>.
>>>>
>>>> --
>>>> Rune Lillesveen
>>>>
>>>> --
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>>>> Groups "blink-dev" group.
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>>>> To view this discussion visit
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>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CACuPfeQQp_NW%3DnoTwk2jpcjGzMb6wFyqj4KGm%3DqpMVyAM767tg%40mail.gmail.com?utm_medium=email&utm_source=footer>
>>>> .
>>>>
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>>> .
>>>
>>
>
> --
> Rune Lillesveen
>
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