Media: Fix Image Editor buttons becoming unreachable via keyboard

[R1shabh-Gupta]

imageEdit.focusManager() unconditionally set tabindex="-1" on whichever element it moved focus to when the Image Editor dialog opened, either an admin notice or, when no notice was present, the first tabbable control in the dialog (such as the Crop button).

This is necessary for the admin notice because it is a <div> and is not natively focusable. However, native controls like <button> elements are already focusable and part of the normal Tab order. Adding tabindex="-1" removes them from that order, and the attribute was never removed afterward.

As a result, when the dialog opened without a notice, the initially focused control was permanently removed from the keyboard Tab order. Repeated open and close cycles progressively affected more controls (Crop, then Scale, then the rotation control, and so on).

This PR limits the tabindex="-1" assignment to the admin notice only. When no notice is present, focus is moved directly to the first tabbable control without modifying its tabindex, preserving the expected keyboard navigation.

Trac ticket: https://core.trac.wordpress.org/ticket/65814

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 5
Used for: Code Review & Testing

---

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.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props rishabhwp.

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

Test using WordPress Playground

The changes in this pull request can previewed and tested using a WordPress Playground instance.

WordPress Playground is an experimental project that creates a full WordPress instance entirely within the browser.

Some things to be aware of

• All changes will be lost when closing a tab with a Playground instance.
• All changes will be lost when refreshing the page.
• A fresh instance is created each time the link below is clicked.
• Every time this pull request is updated, a new ZIP file containing all changes is created. If changes are not reflected in the Playground instance,
  it's possible that the most recent build failed, or has not completed. Check the list of workflow runs to be sure.

For more details about these limitations and more, check out the Limitations page in the WordPress Playground documentation.

Test this pull request with WordPress Playground.