This is a major upgrade for the WordPress editor. There are many changes in 4.0:
- New UI and UI API.
- New theme.
- Revamped events system/API.
- Better code quality, readability and build process.
- Lots of (inline) documentation.
- And generally many improvements everywhere.
All default TinyMCE plugins have been upgraded. The WordPress implementation custom plugins were upgraded too. Looking in the plugin repository, there are a lot of WordPress plugins that add a TinyMCE plugin. Because of all the API changes, most of these plugins would need an update too. If you are the author of such plugin, please test it in trunk now.
Generally there are three groups of TinyMCE plugins added by WordPress plugins:
- Custom plugin created specifically for the WordPress plugin. If you’ve developed this kind of plugin, please see the 3.x to 4.0 migration guide and the 4.0 API documentation.
- WordPress plugins that add third-party or default TinyMCE plugins would (of course) need to be updated to include the 4.0 version of the plugin. The PHP global $tinymce_version can be used to determine which plugin to load.
- Mini-plugins that only add a button to the toolbar. This works pretty much the same. It is advisable to update to use the ‘dashicons’ icon font instead of image icon.