IME composition window appears at screen corner after virtual desktop switch when using SylphyHornPlusWin11

[karasunouta]

Summary:
When using SylphyHornPlus on Windows 11, Japanese IME composition windows (including candidate lists) appear in the top-left corner of the screen after switching virtual desktops.

Steps to Reproduce:

1. Install SylphyHornPlus and run it in the background.
2. Open a Chromium-based app (e.g. Chrome, UpNote).
3. Switch to another virtual desktop using Ctrl+Win+Arrow.
4. Return to the original desktop, where a previously focused text input field (e.g. a textarea) is automatically re-focused.
5. Start typing in Japanese using Google Japanese Input or Microsoft IME.

Expected Behavior:
The IME composition window and candidate list should appear near the text cursor.

Actual Behavior:
The IME composition window and candidate list appear at the top-left corner of the display.

Workaround:
Exiting SylphyHornPlus immediately resolves the issue.

Environment:

• Windows 11 (Version 23H2 / 24H2)
• Google Japanese Input / Microsoft IME
• SylphyHornPlusWin11 v4.0.0-beta.13
• Chrome / UpNote

Note:
This issue does not occur when SylphyHornPlus is not running. It appears that SylphyHornPlus interferes with IME positioning, possibly by modifying window focus or message handling after a desktop switch.

Captured Movie:
Here is a screen recording that demonstrates the behavior using UpNote (and SakuraEditor for comparison).
https://drive.google.com/file/d/1aBorIybXA4H9baS5ox7cKugSZ0pwHVDt/view?usp=drive_link

[karasunouta]

Additional Notes:

• It has been confirmed that this issue does not occur in the input field of Google Keep, even though it runs in the same Chrome environment.
  • This behavior is consistent and reproducible (tested multiple times).
  • In contrast, the issue consistently occurs in other web applications running inside the Chrome browser, such as X (Twitter), Bluesky, and Chatwork.