RFR: 8226990: GTK & Nimbus LAF: Tabbed pane's background color is not expected one when change the opaque checkbox. [v9]

[Harshitha Onkar]

On Thu, 18 Apr 2024 04:47:15 GMT, Abhishek Kumar <abhiscxk at openjdk.org> wrote:

>> 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.
>
> Abhishek Kumar has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Number of tab increased

Tested on Ubuntu, changes look good.

Minor:
Test instructions can be rephrased for clarity.
Copyright years need to be updated for some of source code files.

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Marked as reviewed by honkar (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17720#pullrequestreview-2010302976