WordPress 3.9+ TinyMCE 4 Tweaks: Adding Styles, Buttons, Fonts, Drop-downs & Pop-Ups - WPExplorer
One of my favorite updates in WordPress 3.9 was making the TinyMCE version 4.0 core. The new TinyMCE looks a look cleaner (really matches the WP dashboard) and it has some really nice added functionality. A lot of my old themes and plugins had to be updated to work with the new TinyMCE so I spent some time digging through the API and figuring some cool stuff out. Below I’ll give you some examples on how you can extend the functionality of the TinyMCE. I’m not going to walk you through all the steps or what the code means exactly (this is intended for developers) but will provide you with the exact code you can copy/paste in your theme or plugin and then tweak accordingly.