RFR: 8226990: GTK & Nimbus LAF: Tabbed pane's background color is not expected one when change the opaque checkbox. [v8]

[Harshitha Onkar]

On Wed, 10 Apr 2024 05:25:37 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:
> 
>   Tabs Opaque checkbox handle in synth derived lafs

test/jdk/javax/swing/JTabbedPane/TestJTabbedPaneOpaqueColor.java line 152:

> 150: 
> 151:         layoutButtonPanel.add(scrollButton);
> 152:         layoutButtonPanel.add(wrapButton);

Unless the test frame is resized or there are more number of tabs, the effect of `SCROLL_TAB_LAYOUT` or `WRAP_TAB_LAYOUT` isn't seen.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17720#discussion_r1569742062