RFR: 8226990: GTK & Nimbus LAF: Tabbed pane's background color is not expected one when change the opaque checkbox.

Tue Feb 6 05:51:58 UTC 2024

JTabbedPane's content area, tab area and tab background color are not as expected when opaque is set to true or false. 
The proposed fix is to handle the TabbedPane's background color in installed LAFs. Manual test is added to support the fix and there is no regression caused by the fix. 

Proposed fix is tested in Ubuntu 22.04 and Oracle linux.

CI link is posted in JBS.

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Commit messages:
 - TabbedPane background color fix

Changes: https://git.openjdk.org/jdk/pull/17720/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17720&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8226990
  Stats: 232 lines in 5 files changed: 231 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17720.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17720/head:pull/17720

PR: https://git.openjdk.org/jdk/pull/17720