RFR: 8350048: Enforce threading restrictions for show and hide methods in Window, Control, and Skin [v4]

[Andy Goryachev]

On Tue, 4 Mar 2025 17:14:26 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Have you done a headful test run?

combined branch (this PR + #1697 + #1727) is green on all platforms except for a single unrelated failure on linux: 

`RegionBackgroundFillUITest > testScenario1() FAILED`

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PR Comment: https://git.openjdk.org/jfx/pull/1717#issuecomment-2698771906