[jfx25] RFR: 8359601: Fix window button states of an extended stage

[Michael Strauß]

8359601: Fix window button states of an extended stage

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Commit messages:
 - Backport bc433da812461a1c2796cdb3123f814e4ce532d5

Changes: https://git.openjdk.org/jfx/pull/1855/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1855&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359601
  Stats: 604 lines in 20 files changed: 277 ins; 260 del; 67 mod
  Patch: https://git.openjdk.org/jfx/pull/1855.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1855/head:pull/1855

PR: https://git.openjdk.org/jfx/pull/1855