[Bug] Visual ghosting on left sidebar Threads on hover after opening Git Diff panel

What version of the Codex App are you using (From “About Codex” dialog)?

Version 26.325.31654 (1272)

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Darwin 24.6.0 arm64 arm

What issue are you seeing?

In the Codex Desktop App, hovering over the "Threads" list in the left sidebar works normally by default. However, once the right-side Git Diff panel is opened, hovering over the "Threads" list causes visual artifacts. The hover background state fails to clear and gets "stuck" on previously hovered items, resulting in multiple items appearing highlighted simultaneously.

https://github.com/user-attachments/assets/e81d6dda-98d3-493a-8184-062d6a9483a5

What steps can reproduce the bug?

1. Launch the application.
2. Hover over the items in the left sidebar "Threads" list (observe normal behavior).
3. Click the top-right "Commit" icon to open the right-side Git Diff panel.
4. Move the cursor back to the left sidebar and hover over various items in the "Threads" list.
5. Observe the visual ghosting effect where previous hover states do not disappear.

What is the expected behavior?

The hover background should only apply to the item currently under the cursor and clear immediately when the cursor moves away, regardless of the Git panel's state.

Additional information

_No response_