As we’ve written here before, Atto is Moodle’s powerful, and user friendly page text and label editor with a significant suite of plugins that extend its functionality not to mention being best in class at ensuring accessibility for your site.
The HTML+ plugin was recently updated for compatibility with Moodle 2.9. From Moodle.org HTML+ “provides a version of the HTML plugin with both syntax highlighting and code beautification. It also provides indentation support,” for Atto.
You can download the update for HTML+ here.