RFR: 8343336: Add persistentScrollBars preference [v4]

[Michael Strauß]

On Tue, 26 Nov 2024 20:43:20 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
>> 
>>  - Merge branch 'master' into feature/accessibility-hide-scrollbars
>>  - add platform keys to javadoc
>>  - Change reducedScrollBars to persistentScrollBars
>>  - Add reducedScrollBars preference
>
> modules/javafx.graphics/src/main/native-glass/gtk/PlatformSupport.cpp line 126:
> 
>> 124: 
>> 125:         gboolean overlayScrolling = true;
>> 126:         g_object_get(settings, "gtk-overlay-scrolling", &overlayScrolling, NULL);
> 
> This causes a warning to be printed during initialization on a very old Ubuntu system (16.04) when running any application:
> 
> 
> GLib-GObject-WARNING **: g_object_get_valist: object class 'GtkSettings' has no property named 'gtk-overlay-scrolling'
> 
> 
> I see from the docs that this setting was added in GTK 3.24.9. Perhaps a runtime check is in order? It could be done as a follow-up bug since it is just a warning. It correctly reports `GTK.overlay_scrolling=true` and `persistentScrollBars=false`.

I've added a runtime check for the `gtk-overlay-scrolling` property.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1618#discussion_r1859323447