RFR: 8313424: JavaFX controls in the title bar (Preview) [v86]

[Michael Strauß]

> Implementation of [`StageStyle.EXTENDED`](https://gist.github.com/mstr2/0befc541ee7297b6db2865cc5e4dbd09).

Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:

  add the same fix in childVisibilityChanged

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1605/files
  - new: https://git.openjdk.org/jfx/pull/1605/files/0bb24e18..4a7e57f5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=85
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=84-85

  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1605.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1605/head:pull/1605

PR: https://git.openjdk.org/jfx/pull/1605