The conversation history navigation markers — the small white rectangles on the right side of the main conversation pane — disappear when the left sidebar is resized to certain widths.

What version of the Codex App are you using (From “About Codex” dialog)?

26.707.31428

What subscription do you have?

ChatGPT Plus

What platform is your computer?

Darwin 25.5.0 arm64 arm

What issue are you seeing?

The conversation history navigation markers — the small white rectangles on the right side of the main conversation pane — disappear when the left sidebar is resized to certain widths.

What steps can reproduce the bug?

This issue is reproducible in ChatGPT for macOS version 26.707.31428 on a 16-inch MacBook Pro with a 3456 × 2234 display.

Reproduction steps:

1) Maximize the ChatGTP for macOS version 26.707.31428 first.
2) Resize the left sidebar to its minimum width, approximately 576 px. At this width, the small white navigation markers on the right side of the main conversation pane are visible.
3) Increase the width of the left sidebar to approximately 625 px. The navigation markers disappear.
4) Continue increasing the width of the left sidebar to approximately 825 px. The navigation markers reappear.

Actual behavior:
The navigation markers disappear when the left sidebar is resized to certain intermediate widths.

<img width="722" height="746" alt="Image" src="https://github.com/user-attachments/assets/08e4e1b4-5109-4b93-963c-995dcf579623" />

<img width="783" height="746" alt="Image" src="https://github.com/user-attachments/assets/af0a43f6-c39b-41dd-b548-a22e54564fae" />

<img width="1038" height="746" alt="Image" src="https://github.com/user-attachments/assets/7a563e42-d346-46fd-bb91-7e1f96dd9c76" />

What is the expected behavior?

Expected behavior:
The navigation markers should remain visible regardless of the left sidebar width.

Additional information

_No response_