linux(wayland): proactive text_input enable + fix infinite loop + deduplicate preedit events

[FurryR]

Summary

This PR fixes three issues in the Wayland text-input (IME) handling path in winit:

1. Proactive enable for KWin compatibility — KWin expects zwp_text_input_v3.enable() to be sent *before* the compositor delivers enter. Winit now proactively enables text_input in three places: when a new text_input capability appears, when WlKeyboard::enter fires, and when a new window is created.
2. Infinite loop in Done handler — The upstream Done handler unconditionally emitted Ime::Preedit("") whenever pending_preedit was None, creating a feedback loop: Preedit("") → SetMarkedText("") → set_ime_cursor_area → commit() → another empty done → repeat. The fix consumes pending_commit and pending_preedit before deciding what to emit, emitting nothing when neither is present.
3. Deduplicate redundant preedit events — fcitx5/KWin may send multiple done events with identical preedit text per keystroke. Forwarding all of them floods the application with SetMarkedText dispatches, each triggering a re-render + set_ime_cursor_area + commit() that can overwhelm the compositor. Track the last sent preedit and skip when unchanged.

Changes

File	Change
seat/mod.rs	Register + enable text_input for existing windows in new_capability
window/mod.rs	Pre-populate text_inputs from existing seats on window creation
seat/keyboard/mod.rs	Proactive enable() + commit() on WlKeyboard::enter
seat/text_input/mod.rs	Remove redundant enable/commit from Enter handler; add dedup tracking to Done handler

Testing

Tested on KDE Wayland (Manjaro Linux) with fcitx5 IME. Both Chinese (pinyin) and Japanese (mozc) input work correctly with no crash, no infinite loop, and no broken pipe errors.

[FurryR]

I'm not sure if this change should be added to changelog.

I'm now working on other issues so it may take a long while for me to respond.

If possible you can directly modify CHANGELOG. Thanks for a lot!

[FurryR]

Update:

Chinese IME works while Japanese IME still causes crash. I'm marking this PR as a draft.

[FurryR]

Ready for review.

[FurryR]

This seems irrelevant, but after applying the fix, I'm able to use FeatureFlag::ImeMarkedText on Linux (still need cargo run --feature .

diff --git a/crates/warp_features/src/lib.rs b/crates/warp_features/src/lib.rs
index 3dbdd8b..03a2c93 100644
--- a/crates/warp_features/src/lib.rs
+++ b/crates/warp_features/src/lib.rs
@@ -982,8 +982,6 @@ pub const RELEASE_FLAGS: &[FeatureFlag] = &[
     FeatureFlag::Autoupdate,
     FeatureFlag::Changelog,
     FeatureFlag::CrashReporting,
-    // Marked text is currently only supported on MacOS.
-    #[cfg(target_os = "macos")]
     FeatureFlag::ImeMarkedText,
     // Remote server binary is not yet supported on Windows.
     #[cfg(not(windows))]

But after all this is out of my reach. I'm just testing and it works fine.