RFR: 8280482: Window transparency bug on Linux [v7]

[Alexey Ivanov]

On Fri, 28 Jul 2023 16:57:31 GMT, Tejesh R <tr at openjdk.org> wrote:

>> The bug mentions about transparency issue on Linux which actually got resolved with [JDK-8006421](https://bugs.openjdk.org/browse/JDK-8006421) fix. Now there is another problem related to the bug, which is screen selection going wrong during checking for new screen when the test is run. The problem is that (As seen in the pictures attached in bug) the transparency is lost for windows which are in screen 0 (default screen) too, which is not supposed to happen where windows on screen 1 should have lost there transparency. The main reason being the call to `toGlobal()` when window bounds are passed to `checkIfOnNewScreen` method. I didn't get the actual reason for `toGlobal` being used here (actually not required to check monitor number), but it actually doubled the X position of the window [here]( https://github.com/openjdk/jdk/blob/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5/src/java.desktop/unix/classes/sun/awt/X11/XBaseWindow.java#L776). Removing `toGlobal` solve the issue and neith
 er didn't cause any regression (existing test + the reason `toGlobal()` was added [JDK-8143295](https://bugs.openjdk.org/browse/JDK-8143295)).
>> 
>> The automated test fails if GC is changed for windows within screen 0 (default screen). CI testing is green.
>
> Tejesh R has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review fix

It has fixed the problem, I verified it using the attached reproducer and the automatic test case.

test/jdk/java/awt/Multiscreen/MultiScreenCheckScreenIDTest.java line 86:

> 84:                     "Available : " + screens.length);
> 85:             return;
> 86:         }

In such cases, it's better to use `jtreg.SkippedException` to indicate clearly that the test is not applicable in the current environment.

test/jdk/java/awt/Multiscreen/MultiScreenCheckScreenIDTest.java line 133:

> 131:     public void mouseClicked(MouseEvent e) {
> 132:         ((Window) e.getSource()).dispose();
> 133:     }

In the automatic test, it's not necessary at all — you don't expect any input.

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PR Comment: https://git.openjdk.org/jdk/pull/14825#issuecomment-1660946026
PR Review Comment: https://git.openjdk.org/jdk/pull/14825#discussion_r1281054688
PR Review Comment: https://git.openjdk.org/jdk/pull/14825#discussion_r1281056068