If you are using Distraction Free Mode Writing in WordPress most of the time, then you may have noticed that the editor gets chopped off at smaller sizes. This is annoying especially if you are using a mobile phone or tablet to write a post.
The good news is WordPress promises that this problem will be fixed in the next WordPress update, which is WordPress 3.9. If you really need your DFW , then there is a patch that fixes this issue using a simple CSS fix.
It is also worth mentioning that fullscreen button has been removed in favor of Distraction Free Writing Mode. | Read the rest of the post here: http://wptavern.com/distraction-free-writing-mode-will-be-responsive-in-wordpress-3-9