RFR: 8292922 - [Linux] No more drag events when new Stage is created in drag handler [v4]

[Andy Goryachev]

On Tue, 20 Dec 2022 01:35:14 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This PR  was previously discussed on #905.
>> 
>> The approach is to grab the keyboard focus so the window that originated the drag will keep it.
>> 
>> I did some cleanup on grabbing related functions as well.
>> 
>> `gdk_keyboard_focus()` is deprecated, so is `gdk_device*` functions in favor of `gdk_seat*`. But that's only available in later Gtk versions. I checked and newer Gtk will use `gdk_seat*` inside the deprecated `gdk_keyboard_focus()`.
>
> Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Oh this was it

re-tested the same scenarios.  somehow it feels there is less flicker than before - it's hard to tell in a virtualized environment.

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Marked as reviewed by angorya (Committer).

PR: https://git.openjdk.org/jfx/pull/977