RFR: 8313956: focusWithin on parents of a newly-added focused node is not updated [v2]

[John Hendrikx]

On Fri, 18 Aug 2023 09:16:57 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> modules/javafx.graphics/src/main/java/javafx/scene/Node.java line 8201:
>> 
>>> 8199: 
>>> 8200:         // Since focus changes are atomic, we only fire change notifications after
>>> 8201:         // all changes are committed on all old and new parents.
>> 
>> Is it possible a user can interfere with this process by adding a listener to `focusWithinProperty`?  It fires events when it goes from `true` to `false` and vice versa.
>
> I also noticed this code, which I think will not do the correct thing when `change` is not 1 or -1:
> 
>         void adjust(int change) {
>             count += change;
> 
>             if (count == 1) {
>                 set(true);
>             } else if (count == 0) {
>                 set(false);
>             }
>         }
> 
> For example, if focus within currently is `false`, and it is "adjusted" by 5, the count goes from 0 to 5 in one go.  It will remain `false` then.  Is this intended?

> Is it possible a user can interfere with this process by adding a listener to `focusWithinProperty`? It fires events when it goes from `true` to `false` and vice versa.

Can disregard this, it seems the property uses a special base class that breaks with the general property contract.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1210#discussion_r1298220463