WordPress 4.3 Removes Old DFW

From Old Distraction Free Writing Code Removed in 4.3

This release we removed all old DFW code, which hasn’t been used in coreCore Core is the set of software required to run WordPress. The Core Development Team builds WordPress. since 4.1. We left it in core for two releases so pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party authors had the time to update. If it is essential to your plugin, the files in 4.2 can still be reused and improved. See [32677].

Please make sure you update your plugins before 4.3 is released.