Windows: maximized Codex window shows transparent/desktop bleed-through after 26.527.3686.0 update

Codex Windows app: maximized window shows transparent/desktop bleed-through after update

Environment

• App: Codex Desktop for Windows
• Package: OpenAI.Codex
• Version: 26.527.3686.0
• Install location pattern: C:\Program Files\WindowsApps\OpenAI.Codex_26.527.3686.0_x64__2p2nqsd0c76g0\
• OS: Windows, x64
• Date observed: 2026-05-30

Summary

After updating Codex Desktop on Windows to 26.527.3686.0, the UI renders incorrectly only when the Codex window is maximized. The left sidebar/title/menu area becomes transparent or visually blends with the desktop, so desktop icons and wallpaper show through the Codex UI.

The issue does not appear when Codex is not maximized. It also appears to go away if another application window is open behind Codex, which suggests a Windows DWM / transparent window material / maximized-window composition regression in the Codex desktop shell.

Steps to reproduce

1. Launch Codex Desktop on Windows after updating to 26.527.3686.0.
2. Make sure no other application window is behind Codex; the desktop is directly behind it.
3. Maximize the Codex window.
4. Observe the left sidebar/title/menu area.
5. Restore the window to a non-maximized size.
6. Optionally open another application window behind Codex, then bring Codex to the front.

Actual behavior

• When maximized with the desktop behind it, the left sidebar/title/menu area appears transparent or partially transparent.
• Desktop icons and wallpaper show through the Codex UI.
• The main content area remains mostly normal.

Expected behavior

Codex should render the sidebar/title/menu area with the intended app background whether the window is maximized or restored, regardless of what is behind the window.

Workarounds tried

• Disabled Windows transparency effects.
• Cleared/renamed Codex Web/GPU caches under:
• %APPDATA%\Codex\web\Codex\Default\Cache
• %APPDATA%\Codex\web\Codex\Default\Code Cache
• %APPDATA%\Codex\web\Codex\Default\GPUCache
• %APPDATA%\Codex\web\Codex\Default\DawnGraphiteCache
• %APPDATA%\Codex\web\Codex\Default\DawnWebGPUCache
• Tried launching the internal Codex.exe with GPU flags, but Windows/MSIX blocks direct execution from WindowsApps with Access is denied.
• Keeping Codex non-maximized avoids the issue.
• Keeping another app window behind Codex also avoids or masks the issue.

Notes

This started immediately after the Codex update. The behavior is specific to maximized window state and appears related to the app shell/window background composition rather than user data or local workspace content.

Related public user report:

• https://www.reddit.com/r/codex/comments/1trmu5t/an_incredibly_funny_codex_glitch/