RFR: 8313956: focusWithin on parents of a newly-added focused node is not updated [v4]

[Andy Goryachev]

On Fri, 18 Aug 2023 20:45:00 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> This PR fixes an issue with the way `focusWithin` bits are adjusted in the scene graph. Previously, the `focusWithin` counts of all parents of a removed node would be decreased if the removed node has a non-zero `focusWithin` count. This PR adds logic for the opposite scenario: the `focusWithin` count is increased on all parents of a newly-added node that is already focused (or contains other focused nodes).
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Changes per review

question: what happens when the user navigates away when editing the cell?  it looks like the fix correctly handles the situation.  are there any other possible scenarios?

<img width="644" alt="Screenshot 2023-08-18 at 13 53 02" src="https://github.com/openjdk/jfx/assets/107069028/cab1ffaf-78bf-493a-bf6d-18d8e2525d3c">

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PR Comment: https://git.openjdk.org/jfx/pull/1210#issuecomment-1684427097