In macOS Chrome + AquaSKK (Input Method), Some characters will not converted by IM

[rinsuki]

microsoft/vscode#184777

Details

• Browser and browser version: Google Chrome 137.0.7151.69 (Official Build) (arm64)
• OS version: macOS 15.5（24F74）
• xterm.js version: I'm not really sure, but tested on VSCode 1.100.2 and https://xtermjs.org/ example

Steps to reproduce

1. Enable Hiragana Input in AquaSKK https://github.com/codefirst/aquaskk/releases (by enable AquaSKK input and press Ctrl-J)
2. Type an character which only needs one type (e.g. "a" for "あ", "i" for "い", "-" for "ー")
3. If xterm.js is running on Chromium-based runtime, these characters would not converted by IM and just put actual typed keys (press: "a", expected to see: "あ", actual: "a")

Note:

• If browser isn't Chromium-based (e.g. Safari and Firefox), it would work fine.
• If character requires two or more types (e.g. "ka" for "か"), we could see after converted character in xterm.js even in Chromium-based browser

I think It is because of differences about how browser fires input events, so I will attach screenshot of https://w3c.github.io/uievents/tools/key-event-viewer.html (I typed "aka", expected result is "あか"):

Top one is the Chrome, Left one is the Safari 18.5 (20621.2.5.11.8), Right one is the Firefox Nightly 141.0a1 (2025-06-03) (aarch64)