RFR: 8299968: Second call to Stage.setScene() create sizing issue with uiScale > 1.0

[Kevin Rushforth]

On Tue, 7 Mar 2023 14:33:33 GMT, Lukasz Kostyra <lkostyra at openjdk.org> wrote:

> Issue happened during setting a new Scene - updating a new View was done while the Window reference it kept was null. This caused it to default scaling values to 1.0f (or 100%) while processing a resize notification, which for high DPI screens with scaling different than 100% caused UI issues.
> 
> Resolved by splitting `_setView()` native call into two parts - first one sets the view, then back in JVM side we set a correct Window reference, then we trigger the notification. It has to be triggered from native side, because Windows backend of Glass sends back new width/height pulled from WinAPI `::GetClientRect()` call.
> 
> In process of working on this issue I also found another scenario causing the same problem - calling `Stage.setScene()` after `Stage.show()`. The patch fixed that case as well.
> 
> Added a system test which is supposed to check for above issues. I didn't limit it to run only on platforms with UI scaling enabled because it also serves as a good sanity check in case there are some other changes to code that might move/scale the UI unwantingly. I tested this patch both on macOS Ventura and Windows 11, with `d9c091f` all tests pass while without `d9c091f` on Windows tests `testShowAndSetScene` and `testSecondSetScene` fail as expected.

I'll test and review it. One quick comment: since the newly-added system test uses Robot, the test class will need to move under the `test.robot` hierarchy so it will be correctly excluded unless `-PUSE_ROBOT=true`.

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PR: https://git.openjdk.org/jfx/pull/1054