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

[Andrey Turbanov]

On Tue, 6 Feb 2024 05:43:26 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.

test/jdk/javax/swing/JTabbedPane/TestJTabbedPaneOpaqueColor.java line 96:

> 94:         PassFailJFrame.positionTestWindow(
> 95:                 frame, PassFailJFrame.Position.HORIZONTAL);
> 96:         for( int i = 0; i < NUM_TABS; ++i) {

Suggestion:

        for (int i = 0; i < NUM_TABS; ++i) {

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PR Review Comment: https://git.openjdk.org/jdk/pull/17720#discussion_r1483995592