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Windows: maximized Codex window shows transparent/desktop bleed-through after 26.527.3686.0 update #25217

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Windows: maximized Codex window shows transparent/desktop bleed-through after 26.527.3686.0 update#25217
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appIssues related to the Codex desktop appbugSomething isn't workingwindows-osIssues related to Codex on Windows systems

Description

@rencheng233-maker
rencheng233-maker
opened on May 30, 2026

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:

Activity

  1. github-actions
    added
    bugSomething isn't working
    appIssues related to the Codex desktop app
    windows-osIssues related to Codex on Windows systems
    on May 30, 2026

  2. github-actions commented on May 30, 2026

    @github-actions
    github-actionsBot
    on May 30, 2026 – with GitHub Actions
    Contributor

    Potential duplicates detected. Please review them and close your issue if it is a duplicate.

    Powered by Codex Action

  3. ycfhgryj commented on May 30, 2026

    @ycfhgryj
    ycfhgryj
    on May 30, 2026 – with ChatGPT Codex Connector

    Confirming this repro on another Windows machine.

    Environment:

    • Codex Desktop for Windows, Microsoft Store package 9PLM9XGG6VKS
    • Codex version: 26.527.3686.0
    • OS: Microsoft Windows 10 Home 10.0.19045 x64
    • Observed after the update on 2026-05-29; the same machine did not show this on 2026-05-28.

    Behavior:

    • The issue happens only when the Codex window is maximized/fullscreen.
    • The left/sidebar area becomes transparent and shows whatever is behind the app.
    • The transparent left area is still interactive/clickable, so this looks like a paint/composition problem rather than missing UI elements.
    • Restoring the window to a non-maximized size makes the UI render normally.

    Things tried that did not fix it:

    • Reinstalling Codex from Microsoft Store.
    • Resetting/renaming %APPDATA%\Codex user data.
    • Clearing GPU/Code/Shader/Dawn caches.
    • Turning off Windows transparency effects.
    • Trying to launch with GPU-disable flags; the Store/MSIX app entry does not appear to preserve those flags for the main process.

    Current workaround:

    • Use a large non-maximized window, e.g. nearly full screen but with isMaximized=false in .codex-global-state.json.

    This strongly appears tied to the maximized-window rendering path in the current Windows build.

  4. rencheng233-maker commented on May 30, 2026

    @rencheng233-maker
    rencheng233-maker
    on May 30, 2026
    Author

    OH, this problem is solved.
    It's an issue with the settings in the new version of Codex.
    In Appearance -- Translucent sidebar, there is a switch. Turning it on makes the sidebar transparent, and turning it off makes it normal.

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