RFR: 8353685: Open some JComboBox bugs 4 [v2]

[Alisen Chung]

> Updating and opening some JComboBox bugs

Alisen Chung has updated the pull request incrementally with one additional commit since the last revision:

  move disposal onto edt

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24733/files
  - new: https://git.openjdk.org/jdk/pull/24733/files/94f10115..0799d454

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24733&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24733&range=00-01

  Stats: 26 lines in 3 files changed: 7 ins; 10 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/24733.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24733/head:pull/24733

PR: https://git.openjdk.org/jdk/pull/24733