RFR: 8313424: JavaFX controls in the title bar [v23]

[Michael Strauß]

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

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

  refactor performWindowDrag

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1605/files
  - new: https://git.openjdk.org/jfx/pull/1605/files/8974c141..ca9b325a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=22
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=21-22

  Stats: 18 lines in 3 files changed: 9 ins; 8 del; 1 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