RFR: 8305418: [Linux] Replace obsolete XIM as Input Method Editor [v31]

[Martin Fox]

On Thu, 12 Dec 2024 11:41:20 GMT, Helly Guo <duke at openjdk.org> wrote:

>> Finally, I got the point. Fcitx5 has a setting entry: `Show preedit in application`. If this is on, it works well. If this is off, the value `im_ctx.on_preedit` will get `false` when im(`fcitx5`) finished input-action. Then, the input will not show in the TextField.
>> 
>> ![wechat_2024-12-12_193021_345](https://github.com/user-attachments/assets/9cab3844-8166-43fe-b69d-bda00f422e90)
>
> ![pic_20241212193112](https://github.com/user-attachments/assets/7b9233f9-3af5-42d5-89f9-9f85248d68dd)
> 
> The option is surrounded by a red box.

@hellyguo Thanks so much for tracking this down and providing all the details. I would like to better understand what that checkbox does but I might not be able to get to that until next week.

JavaFX handles keyboard entry using two mechanisms, KeyEvents and InputMethodEvents. This corresponds to the way Windows works. On Mac and Linux the OS only uses one channel (basically InputMethodEvents) and we have to apply a simple heuristic to map this to JavaFX's two-channel approach. This checkbox seems to be upsetting that logic.

(I work on the Mac side of this and @tsayao works on the Linux side. I just do testing on Linux because it's easy for me to create new virtual machines.)

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/1080#discussion_r1882371128