RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v25]

[Lukasz Kostyra]

On Wed, 21 Aug 2024 09:58:53 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This replaces obsolete XIM and uses gtk api for IME.
>> Gtk uses [ibus](https://github.com/ibus/ibus)
>> 
>> Gtk3+ uses relative positioning (as Wayland does), so I've added a Relative positioning on `InputMethodRequest`.
>> 
>> [Screencast from 17-09-2023 21:59:04.webm](https://github.com/openjdk/jfx/assets/30704286/6c398e39-55a3-4420-86a2-beff07b549d3)
>
> Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove negative checks

I have an issue in IMETest with the new patch. This does not happen on master, so I suspect it's a regression.

I tried typing with polish keyboard and it seems like it does not pick up the special characters which use diacritical signs - ą, ć, ę, ł, ń, ó, ś, ż, ź. Polish keyboard layout (known in Ubuntu simply as "Polish", in Windows as "Polish (programmers)") invokes those by using a combination of Right Alt + respective key so to get the above. The only exception is ż and ź:
- Right Alt + Z == ż
- Right Alt + X == ź

It seems like something recognizes those characters in the background, as I do get `Released: <character>` message in the console, but nothing shows up in the Text Area of IMETest. On master I do get `Pressed: <character>` messages when trying to type those characters, so I suspect some event does not fire.

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Changes requested by lkostyra (Committer).

PR Review: https://git.openjdk.org/jfx/pull/1080#pullrequestreview-2342265459