On Sat, 7 Nov 2026 17:04:02 GMT, Marius Hanl <[email protected]> wrote:

>> The third split PR of the CSS saga™.
>> 
>> In this episode, I have  a cornercase, but still a valid bug, found in 
>> https://github.com/openjdk/jfx/pull/2225.
>> 
>> In JavaFX, there is this rule where `USER < AUTHOR` style. That is, CSS will 
>> set the property value, e.g. opacity, to the value defined in the `Scene` 
>> stylesheet and ignore if the value was set by a setter.
>> 
>> It is still possible to overwrite such value by a setter, but it will be 
>> reapplied in the very next CSS pass.
>> 
>> Now, when we apply a style in a listener which is called during CSS reset, 
>> this style may override the CSS value.
>> This only happens when you style a property that is defined before the 
>> property you are listening to.
>> 
>> A CSS style reset is the operation to set the property value to the original 
>> value because it is not styled anymore (e.g. because we removed or added a 
>> `PseudoClass`).
>> 
>> ---
>> 
>> Example: `Node`'s `CssMetaData` adds `OPACITY` first and later `TRANSLATE_X`.
>> 
>> So opacity is reset first, then `translateX`. If we now set the `opacity` in 
>> a `translateX` listener, we can successfully override the `opacity`.
>> 
>> The very next CSS pass will however recover this (e.g. calling `applyCss` 
>> again).
>> This is not needed anymore with the fix.
>> 
>> ---
>> 
>> I added two tests, they are basically the same, just the order is changed.
>> - The first test failed before, because it sets the `opacity` in a 
>> `translateX` listener
>> - The second test succeeds before and after, because it sets the 
>> `translateX` in a `opacity` listener
>> 
>> Again, shows: `OPACITY` is processed first, later `TRANSLATE_X`, which with 
>> the fix does not matter anymore.
>> I reused the existing reset property logic. It is now called like before, 
>> and as part of this fix.
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Marius Hanl has updated the pull request with a new target base due to a 
> merge or a rebase. The incremental webrev excludes the unrelated changes 
> brought in by the merge/rebase. The pull request contains five additional 
> commits since the last revision:
> 
>  - Merge branch 'master' of https://github.com/openjdk/jfx into 
> 8394228-Property-value-set-by-a-listener-during-CSS-reset-is-not-overridden-by-its-style
>  - change var
>  - (re)track a property after reset failed. Add as CSS error.
>  - unsettable property
>  - 8394228: Property value set by a listener during CSS reset is not 
> overridden by its style

Marked as reviewed by jhendrikx (Reviewer).

-------------

PR Review: https://git.openjdk.org/jfx/pull/2343#pullrequestreview-5814382023

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