macOS Computer Use: clicks can be offset on multi-monitor setups with negative display coordinates

Summary

On macOS with multiple displays, Computer Use can place the cursor visually over a target in a standard system file dialog, but the click is delivered to a different UI element.

Reproduction

1. Use Codex Desktop on macOS with a multi-monitor arrangement where at least one display is positioned below the primary display (therefore using negative coordinates).
2. Have Computer Use open a standard macOS save/open sheet.
3. Ask it to select Downloads in the sheet sidebar.

Expected

The item shown beneath the cursor is selected.

Actual

The cursor was visually over Downloads, but the click selected Recents instead. Repeated attempts showed the same mismatch.

Impact

Automated UI work is unreliable in file dialogs on this display arrangement and can target an unintended destination.

Notes

This report is based on direct observation during a Codex Desktop session. The likely cause is a coordinate-space conversion issue between displays, but that is an inference rather than a confirmed root cause.