Windows: + composer menu cannot scroll to top at large app font size

What version of the Codex App are you using?

OpenAI.Codex AppX package version 26.721.4979.0.

What platform is your computer?

• Windows 11 Home
• Windows version/build: 10.0.26200 / build 26200
• Primary display: 1280 × 720
• Windows display scaling: 150%

What issue are you seeing?

At a large Codex app font size, clicking the + button in the message composer opens a menu that is taller than the available space. The menu scrolls, but its upward scroll limit prevents reaching the top of the list.

This creates an accessibility problem: the text size that is comfortable to read makes some entries in the + menu unreachable.

What steps can reproduce the bug?

1. Use Codex Desktop on Windows with a 1280 × 720 display and Windows scaling set to 150%.
2. Increase the Codex app font size with Ctrl++.
3. Click the + button in the message composer.
4. Scroll upward inside the opened menu.

Actual result:
The menu scrolls, but stops before reaching the top of the list. Maximizing the app window, restarting Codex, and pressing Home while the menu is open do not expose the top.

Workaround:
Reduce the Codex app font size with Ctrl+- until the full menu fits. This restores access to every menu entry, but makes the app text smaller than the preferred readable size.

What is the expected behavior?

The + menu should constrain itself to the available viewport and allow scrolling through every entry at all supported app font sizes. Scrolling upward should always reach the first menu item.

Additional information

This appears related to the combination of Windows display scaling and Codex app font size. Related reports include #23024 (composer layout at 150% Windows scaling) and #23139 (app-level scaling and clipping), but neither appears to describe this specific + menu scroll-boundary problem.