RFR: 8313424: JavaFX controls in the title bar (Preview) [v76]

[Michael Strauß]

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

Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 98 commits:

 - add explicit cast in glass_window.cpp
 - Merge branch 'master' into feature/extended-window
 - Merge branch 'master' into feature/extended-window
 - javadoc
 - Merge branch 'master' into feature/extended-window
 - reapply overlay CSS
 - Merge branch 'master' into feature/extended-window
 - simplify header area picking
 - Fix top resize border on Windows
 - Merge branch 'master' into feature/extended-window
 - ... and 88 more: https://git.openjdk.org/jfx/compare/5d367530...b85f72f3

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Changes: https://git.openjdk.org/jfx/pull/1605/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=75
  Stats: 6805 lines in 76 files changed: 6114 ins; 517 del; 174 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