RFR: 8354943: [Linux] Simplify and update glass gtk backend: window sizing, positioning, and state management issues [v67]

[Kevin Rushforth]

On Wed, 15 Oct 2025 18:46:20 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This is a continuation to [JDK-8236651](https://bugs.openjdk.org/browse/JDK-8236651) and it aims to stabilize the linux glass gtk backend.
>> 
>> This is a refactor of the Glass GTK implementation, primarily focused on window size, positioning, and state management to resolve numerous issues.
>> 
>> The main change is that GtkWindow (which is a GtkWidget) has been replaced with a direct use of GdkWindow for windows. This makes sense because GTK includes its own rendering pipeline, whereas JavaFX renders directly to the underlying system window (such as the X11 window) via Prism ES2 using GL and GLX. Most GTK window-related calls have equivalent GDK calls. Since GDK serves as an abstraction over the system window and input events, it aligns better with the purposes of Glass. Additionally, using GTK required various workarounds to integrate with Glass, which are no longer necessary when using GDK directly.
>> 
>> It uses a simple C++ Observable to notify the Java side about changes. This approach is more straightforward, as notifications occur at many points and the previous implementation was becoming cluttered.
>> 
>> Previously, there were three separate context classes, two of which were used for Java Web Start and Applets. These have now been unified, as they are no longer required.
>> 
>> Many tests were added to ensure everything is working correctly. I noticed that some tests produced different results depending on the StageStyle, so they now use @ParameterizedTest to vary the StageStyle.
>> 
>> A manual test is also provided. I did not use MonkeyTester for this, as it was quicker to simply run and test manually:`java @build/run.args tests/manual/stage/TestStage.java `
>> 
>> While this is focused on XWayland, everything works on pure Xorg as well.
>
> Thiago Milczarek Sayao has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 81 commits:
> 
>  - Merge branch 'master' into 8354943
>    
>    # Conflicts:
>    #	modules/javafx.graphics/src/main/native-glass/gtk/glass_window_ime.cpp
>  - Merge branch 'master' into 8354943
>  - Fix copyright header
>  - Revert "8367898: Skip StageFocusTest on Linux"
>    
>    This reverts commit c95cdcdc9cd8b3070e8076ea91234772d6a21331.
>  - Merge branch 'master' into 8354943
>  - Remove unused imports
>  - - Fix StageOwnershipTest label + minor adjustments
>  - Merge branch 'master' into 8354943
>  - Merge branch 'master' into 8354943
>  - - Fix scene resize when window is unresizable
>  - ... and 71 more: https://git.openjdk.org/jfx/compare/38300ca6...07d1cd31

tests/system/src/test/java/test/javafx/stage/SizingTest.java line 159:

> 157:     void minSize(StageStyle stageStyle) {
> 158:         // JDK-8364547
> 159:         assumeTrue(!PlatformUtil.isWindows());

I can confirm that PR #1870 fixes the underlying bug, JDK-8364547. Once that PR is integrated, merge master and then remove this `assumeTrue`.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1789#discussion_r2433889944