RFR: 8273379 - GTK3 stops sending key events during drag and drop [v10]

[Thiago Milczarek Sayao]

On Wed, 4 Jan 2023 00:44:10 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This PR fixes 8273379.
>> 
>> I reverted back to use GDK (from [8225571](https://bugs.openjdk.org/browse/JDK-8225571)) to handle the events. 
>> 
>> It may also fix [8280383](https://bugs.openjdk.org/browse/JDK-8280383).
>> 
>> There's also some cleaup.
>> 
>> The most changed part is that I had to move `process_events` to `glass_evloop`  because it's reused in glass_dnd.
>> 
>> To do general testing:
>> `java @build/run.args -jar apps/toys/DragDrop/dist/DragDrop.jar`
>
> Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Gtk2 fixes

> This will need a lot of careful testing.
> 
> Can you provide more information about why undoing the changes from [JDK-8225571](https://bugs.openjdk.org/browse/JDK-8225571) is the best approach? Also, have you tested that the various issues that were fixed by JDK-8225571 won't regress as a result?
> 
> /reviewers 2

It's the way I have found to work with key events to fix the bug. The first approach was to use the existing code, but I could'n make it work. I've done a fair bit of testing on Ubuntu 16.04, 22.04 ( the last with wayland and Xorg). 

This patch also introduces mouse grab break handling and interrupts the DND if it occurs. I will attach a test case for this.

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PR: https://git.openjdk.org/jfx/pull/986