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

[Thiago Milczarek Sayao]

On Wed, 6 Sep 2023 16:41:24 GMT, Martin Fox <mfox 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)
>
> I ran into similar failures when I added a method to a core class but did not add it to the Stub version of the same class. In my case I added a call to Stage.java but didn't add it to SubStage.java.
> 
> I'll be away from my computer for about a week and will take a closer look at this when I get back. I did notice that when I press a dead key the caret ends up at the beginning of the preview string when it should be at the end. There's also an issue with the way keys on the numeric keypad are being encoded. The fix is minor (I think) and I'll send details when I get back. Beyond that I don't understand the IME machinery so here's hoping that someone who does can spare some cycles to review this.

There's a bug when closing the window with a key, as pointed by @beldenfox on #1307.

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PR Comment: https://git.openjdk.org/jfx/pull/1080#issuecomment-1868527856