Codex Desktop transparency/compositing bug when focused and maximized on Windows 10 + NVIDIA

Summary

Codex Desktop has a rendering/compositing bug on Windows 10 where the app window becomes partially transparent and shows the Chrome/YouTube window behind it. The bug appears only when Codex is focused and maximized/fullscreen.

Environment

• App: OpenAI Codex Desktop
• App package version: 26.527.3686.0
• Executable version: 148.0.7778.179
• Install path: C:\Program Files\WindowsApps\OpenAI.Codex_26.527.3686.0_x64__2p2nqsd0c76g0\app\Codex.exe
• OS: Windows 10 Enterprise
• OS build: 19045
• Architecture: 64-bit
• GPU: NVIDIA GeForce GTX 1060 6GB
• GPU driver: 32.0.15.8180
• Driver date: 2025-10-29

Actual behavior

When Codex is focused and maximized/fullscreen, content from a background Chrome/YouTube window becomes visible through the Codex UI. Text and icons from the background window overlap with Codex UI elements.

Expected behavior

Codex should render as an opaque foreground app window. Background apps should not be visible through the Codex UI.

Important observations

• If I click outside Codex and Codex loses focus, the artifact disappears.
• If I click back into Codex, the transparency/compositing artifact returns.
• If the Codex window is restored/non-maximized, the bug does not appear.
• If the Codex window is maximized/fullscreen, the bug appears again.
• Clearing MSIX Electron GPU/Code/Dawn caches did not help.
• Directly launching Codex.exe from WindowsApps with Chromium GPU flags failed with Access is denied, so GPU flags could not be tested that way.

Reproduction notes

1. Open Google Chrome with YouTube in the background.
2. Open Codex Desktop.
3. Maximize Codex.
4. Click into Codex so it is focused.
5. Observe Chrome/YouTube content visible through the Codex window.
6. Click outside Codex.
7. Observe the artifact disappear.
8. Click back into Codex.
9. Observe the artifact return.

Attachments

Attach screenshots showing:

• Codex restored/non-maximized without the bug.
• Codex focused + maximized with the transparency/compositing bug.

<img width="1920" height="1007" alt="Image" src="https://github.com/user-attachments/assets/96d1ba31-b935-4c3a-a5ee-04db5d7efbd4" />