Unnecessary horizontal scrollbar on theme-editor.php in WordPress 7.0 RC1

[hardik2812]

On the theme editor page (theme-editor.php) in the WordPress admin dashboard, a horizontal scrollbar is visible even when there is no content overflowing the container.

Steps to reproduce:

Install WordPress 7.0 RC1
Go to Admin Dashboard
Navigate to Appearance → Theme File Editor
Observe the horizontal scrollbar at the bottom

Expected result:
No horizontal scrollbar should appear when content fits within the viewport.

Actual result:
A horizontal scrollbar is displayed unnecessarily, even when there is no overflow content.

Suggested Fix Idea
#templateside>ul {
overflow-x: hidden;
}

[audrasjb]

Thanks for the ticket.
I wasn't able to reproduce the issue on my side in WP 7.0 RC1 (using Chrome on an MBpro). Do you have a very large (or small) screen? A specific configuration? What is you OS/browser?

Obviously moving the severity to normal ;)

[hardik2812]

Hello @audrasjb ,

I have checked in Chrome on a MacBook, and below max-width: 782px.

Thanks

[desrosj]

Setting to trunk until it can be reproduced in an earlier version in case it is related to the admin changes in 7.0.

[hardik2812]

Okay

[wildworks]

I tested this issue in the playground. It's a problem that has been occurring since at least version 6.3, and possibly earlier.

[torontodigits]

Got a chance to test this via PlayGround by installing frresh WordPress RC2 & can see this issue on mobile & can replicate it on very large screens by Zooming it to 200%.

[torontodigits]

Reproduceable Issue on mobile - Ticket #64956

[torontodigits]

Reproduceable Issue on large screens - Ticket #64956

Trac ticket: https://core.trac.wordpress.org/ticket/64956

## Use of AI Tools

• None
• Asked claude to review and provide a solution, but was not able to. Kept on searching and searching and hallucinated itself.

---
This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See ​GitHub Pull Requests for Code Review in the Core Handbook for more details.

## Screencast

​https://app.godam.io/web/video/015u0a9adt

[nikunj8866]

Test Report

Description

✅ This report validates that the patch works as expected.

Patch tested: ​https://github.com/WordPress/wordpress-develop/pull/11588

Environment

• WordPress: 7.1-alpha-20260416.100837
• PHP: 7.4.33
• Server: PHP.wasm
• Database: WP_SQLite_Driver (Server: 8.0.38 / Client: 3.51.0)
• Browser: Chrome 146.0.0.0
• OS: Windows 10/11
• Theme: Twenty Twenty-Five 1.4
• MU Plugins: None activated
• Plugins:
  • Test Reports 1.2.1

Steps to Test

1. Apply the patch from the linked pull request to a WordPress installation.
2. Navigate to Tools > Theme File Editor (theme-editor.php).
3. Resize the browser window to a small viewport width (e.g., below 768px or mobile-sized).
4. Observe whether a horizontal scrollbar appears on the Theme Files section.
5. Navigate to Tools > Plugin File Editor (plugin-editor.php).
6. Again, resize the browser window to a small viewport width.
7. Observe whether a horizontal scrollbar appears on the Plugin Files section.

Actual Results

1. ✅ Issue resolved with patch.
2. Unnecessary horizontal scrollbar on theme-editor.php is resolved with the patch — no horizontal scroll at small widths.
3. Unnecessary horizontal scrollbar on plugin-editor.php is also resolved — no horizontal scroll at small widths.
4. ✅ Patch also tested on WordPress 6.3 — working as expected with no regressions.

Supplemental Artifacts

​https://www.awesomescreenshot.com/video/51596248?key=ffed62429a24e4a0d7a07e4fa4de3983