## Summary The Codex Windows desktop app leaks a thin vertical strip of its maximized window onto the adjacent monitor in a dual-monitor setup. Other Windows applications maximize correctly and stay within the selected monitor. ## Environment - Product: Codex desktop app on Windows - OS: Windows 11 - Codex app version: `26.601.2237.0` - Display setup: dual-monitor display - Date observed: 2026-06-03, Asia/Seoul timezone ## Steps to reproduce 1. Use Windows 11 with a dual-monitor setup. 2. O

Potential duplicates detected. Please review them and close your issue if it is a duplicate. - #25826 *Powered by [Codex Action](https://github.com/openai/codex-action)*

🩹 Codex Windows app maximized window leaks thin strip onto adjacent monitor

Resolved 💬 2 comments Opened Jun 3, 2026 by Lee-Seonyong Closed Aug 6, 2026

💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

Summary

The Codex Windows desktop app leaks a thin vertical strip of its maximized window onto the adjacent monitor in a dual-monitor setup. Other Windows applications maximize correctly and stay within the selected monitor.

Environment

Product: Codex desktop app on Windows
OS: Windows 11
Codex app version: 26.601.2237.0
Display setup: dual-monitor display
Date observed: 2026-06-03, Asia/Seoul timezone

Steps to reproduce

Use Windows 11 with a dual-monitor setup.
Open the Codex desktop app.
Move Codex to one monitor.
Maximize the Codex window using the normal window maximize control.
Observe that a thin vertical strip of the Codex window appears on the adjacent monitor.
Click the adjacent monitor.
Observe that the leaked strip briefly flickers/repaints.

Expected behavior

When maximized, the Codex window should remain fully contained within the selected monitor, like other Windows applications.

Actual behavior

A thin vertical strip of the Codex window extends onto the adjacent monitor. When focus changes by clicking the adjacent monitor, the strip briefly flickers/repaints; for a split second the desktop wallpaper appears, then the Codex strip appears again.

Additional details

F11 fullscreen mode appears normal.
The issue only occurs with the normal maximized window state.
Other applications on the same system maximize correctly and do not cross the monitor boundary.

This looks like a maximized-window frame/bounds calculation issue specific to the Codex Windows desktop app rather than a general Windows display configuration problem.

View original on GitHub ↗

2 Comments

github-actions[bot] contributor · 2 months ago

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

#25826

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ilsurgareev · 1 month ago

Confirmed that this issue is still reproducible on a newer Codex Windows build.

Environment:

Codex desktop package: 26.721.4979.0 x64
Windows 11 25H2, build 26200.8875
Two 3840×2160 monitors
Both monitors use 125% scaling
Displays are aligned exactly: primary (0, 0), secondary (3840, 0)

Measured bounds while Codex is maximized on the primary monitor:

Primary working area: L=0 T=0 R=3840 B=2100
Codex window bounds: L=-9 T=-9 R=3849 B=2109
Codex client bounds: L=-1 T=-1 R=3841 B=2101

Therefore, the outer window/frame extends 9 pixels onto the adjacent monitor, while the client area itself extends 1 pixel onto it.

The secondary display was initially offset vertically by 6 pixels. After aligning both displays to Y=0, the issue remained unchanged, so it does not appear to be caused by display arrangement. Other applications maximize within the selected monitor correctly.