Windows: thin Codex window strip appears on HDMI monitor when maximized

[JamaAlex]

Environment

• Surface: Codex desktop app
• Codex version: 26.917.9434.0
• OS: Windows 11 Pro, build 26200
• Display setup: laptop’s built-in display plus an external monitor connected over HDMI
• Model/plan: Not relevant to this display issue

Bug

When I maximize Codex on the laptop’s built-in display, a very narrow strip of the Codex window appears on the HDMI monitor. I do not see the same behavior consistently in other apps.

Expected: the maximized Codex window stays entirely within the laptop display.

Reproduction

1. Use the laptop display and the external HDMI display.
2. Open Codex on the laptop display.
3. Maximize the Codex window.
4. Observe a narrow strip of the window on the external display.

Diagnostics

This is a visual issue; there is no error message. I have not measured the strip or recorded the exact time it happens.

A similar report was closed here:

Maximized Codex window bleeds onto adjacent monitors in a multi-monitor setup

When the Codex desktop window is maximized on my primary monitor, a thin sliver of the window (roughly 7 to 8 pixels) extends past the left and right edges of that monitor and renders onto the two adjacent monitors. The window content paints into the standard Windows maximize overscan region instead of being clipped to the monitor’s work area. Expected behavior When maximized, the window should fill the primary monitor exactly and remain fully contained within its bounds. No part of the wi…

[EricGT]

Welcome to the forum!

You posted this in the appropriate place on the forum for discussing and documenting a Codex bug. The forum, however, is not the official issue tracker. If the problem needs to be formally reported and tracked by the Codex maintainers, the official place is the OpenAI Codex GitHub issue tracker.

Thanks for following the posting requirements for the Codex Bugs subcategory:

Read this before you post in the Codex Bugs category

Report reproducible bugs in the Codex CLI, IDE extension, app, or web experience. Include your Codex version, environment, steps to reproduce, and expected versus actual behavior. Provide a minimal reproducible example where possible. Model hallucinations or differences in generated output alone are not considered bugs for this category. Keep each topic focused on one bug. Use the main Codex category for discussions and Feature Requests for proposed improvements. When a fix is available, con…

I asked ChatGPT to search for the closest related issue, and it identified:

Windows Desktop: maximized window spills onto adjacent monitors in multi-monitor setup

If that issue describes the same problem you are experiencing, consider adding a reaction to the GitHub issue itself, rather than only reacting to this forum topic. GitHub reactions can help the maintainers gauge how many users are affected.

If it does not match your problem closely enough, search the existing Codex issues for a better match. If you cannot find one, consider opening a new issue and include as much relevant information as possible, such as your Codex version, operating system, environment, reproduction steps, expected behavior, actual behavior, and any relevant logs or error messages.