I have given this request my full support (3 votes) as this is a critical update for both stability and security.

To add to the reasons for this upgrade: the currently bundled TinyMCE v4.7.11 has a known compatibility issue that causes JavaScript errors and prevents the rich text editor from loading in Firefox.

This is a functional bug that impacts admin usability. I was able to resolve this issue locally by manually replacing the files in /assets/js/tinymce/ with those from the final v4.x release, v4.9.11. This confirms that the problem lies with the outdated library version.

However, since the entire TinyMCE version 4 branch is now end-of-life and no longer receives security patches, a simple update to v4.9.11 is only a temporary fix. A full upgrade to a modern, supported version (like v8.2.1) is essential to resolve this browser bug and, more importantly, to ensure the editor component does not become a security liability for WHMCS installations.

This upgrade is necessary to maintain a professional, reliable, and secure platform.