RFR: 8296621: Stage steals focus on scene change

[Thiago Milczarek Sayao]

On Wed, 9 Nov 2022 00:53:19 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> Simple fix to not requestFocus() on scene change.
> 
> The attached bug sample shows that the TextField focused on the scene remains focused when the scene comes back.

> I agree that changing from one scene to another should not cause a new request focus call. My only concern is to ensure that this will not cause any regressions for the initial setting of a scene. A safer change might be to qualify the existing call to `requestFocus` with a check of the previous scene, and only call it if `oldScene == null`.
> 
> /reviewers 2

The reason I found this is that `requestFocus()` in glass native side was being called before the window was visible. I'm not sure about windows or macos, but requesting focus on a unmapped window doesn't work (on Linux) and it seems logical to me. Considering that the usual scenario is to `setScene()` and then `show()`.

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PR: https://git.openjdk.org/jfx/pull/940