[jdk17u-dev] RFR: 8218474: JComboBox display issue with GTKLookAndFeel

[Goetz Lindenmaier]

I think this is a good fix to have in 17.
The tests pass, the new one reproduces the error without the fix.

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Commit messages:
 - Backport c4449224bbb70d1a0256ebf19297450ab0f98d4b

Changes: https://git.openjdk.org/jdk17u-dev/pull/3324/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3324&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8218474
  Stats: 182 lines in 5 files changed: 180 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3324.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3324/head:pull/3324

PR: https://git.openjdk.org/jdk17u-dev/pull/3324