[jfx24] RFR: 8348744: Application window not always activated on macOS 15

[Kevin Rushforth]

Clean backport of macOS 15 activation fix to the `jfx24` stabilization branch.

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Commit messages:
 - Backport f55f5c609f67c1f7a8b8107d6ab1c6945fc44506

Changes: https://git.openjdk.org/jfx/pull/1687/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1687&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348744
  Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1687.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1687/head:pull/1687

PR: https://git.openjdk.org/jfx/pull/1687