RFR: 8329471: Remove GTK2 [v4]

[Alexander Zvegintsev]

On Wed, 31 Jul 2024 18:29:57 GMT, Phil Race <prr at openjdk.org> wrote:

>> Alexander Zvegintsev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   more cleanup
>
> src/java.desktop/share/classes/com/sun/java/swing/plaf/gtk/GTKPainter.java line 215:
> 
>> 213:         if (gtkState == SynthConstants.MOUSE_OVER) {
>> 214:             if (GTKLookAndFeel.is3()) {
>> 215:                 paintComponentBackground(context, g, x, y, w, h);
> 
> So do we really need the is3() check ?? Seems like not to me. Same for the case below at line 573.

It is not the only place, I doubted it, but now updated to remove all usages.
However, prefer to keep the `is3` method itself.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20378#discussion_r1698984338