Windows app renders incorrectly with black bars until Windows dark theme is forced

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

26.415.1938.0

What subscription do you have?

Enterprise

What platform is your computer?

OS: Windows 10 IoT Enterprise LTSC 2021 - OS build: 19044

What issue are you seeing?

### Summary
On Windows, the Codex desktop app rendered incorrectly with large black bars / black regions in the window.
Reinstalling the app did not fix it.

The issue was resolved only after forcing Windows dark theme for apps and system UI.

### What I tried

1. Uninstalled and reinstalled the Codex desktop app from Microsoft Store.
2. Disabled Windows transparency.
3. Forced Windows light theme:

• AppsUseLightTheme=1
• SystemUsesLightTheme=1

1. Restarted the app after each change.

None of the above fixed the rendering issue.

### What fixed it
Forcing Windows dark theme fixed the rendering issue immediately after restarting the app:

• AppsUseLightTheme=0
• SystemUsesLightTheme=0

At the time this worked, Windows transparency was also disabled:

• EnableTransparency=0

### Notes
Before testing, AppsUseLightTheme and SystemUsesLightTheme were not explicitly present in the registry, so Windows
was using its default/policy behavior rather than a forced light or dark value.

This may be a Windows-specific rendering/composition issue related to:

• theme detection / fallback behavior
• Electron/Chromium rendering under certain Windows theme states

I cannot provide a guaranteed minimal repro yet, but the issue occurred in a state where:

• Windows was not explicitly forced to dark mode
• forcing light mode did not help
• forcing dark mode did help

explicit AppsUseLightTheme / SystemUsesLightTheme values.

### Actual behavior
The app rendered with black bars / incorrect black regions until dark mode was explicitly forced.

What steps can reproduce the bug?

Environment

• Codex app version: 26.415.1938.0
• OS: Windows 10 IoT Enterprise LTSC 2021
• OS build: 19044
• GPU/renderer context observed by the app: Microsoft Basic Render Driver

### Symptoms

• The Codex app window opened and was usable, but rendered with obvious black bars / black regions.
• The issue persisted across uninstall/reinstall.
• The issue appeared to be tied to Windows appearance/composition settings rather than app installation state.

What is the expected behavior?

Expected

The sidebars should be visable

Additional information

_No response_