New Layout Option: There is now a new layout option in WordPress 4.0 – the Infinite Scroll. If you click on the grid icon (highlighted in yellow below) you now have the option to have a grid layout with all of your media on one page. To view more, simply use your mouse to scroll down. It functions the same as a Pinterest feed. No more clicking through pages to find an older image or PDF.
Image Details: With the new Media Library functionality, you can edit the details of your media right from the main Library page. If you click on an image, a pop-up will appear with your image details (Title, Alt Tag, URL, etc.).
Note: While in this window, you can use the arrows keys to scroll through your media. Use the ESC key to exit. Or, if you prefer, you can use the buttons at the top of the pop-up (highlighted in yellow below) to scroll or exit.
Uploading Media: Instead of refreshing to a new screen to upload media to the Library, when you click the “Add New” button at the top of the Library page, WordPress now allows you to upload directly on that page. Once the media has finished uploading, you have all the same functionality of infinite scrolling and the pop-up box to edit the details. This helps streamline your process allowing you to do everything from one page.
Note: If you click on the “Add New” from the lefthand options in the dashboard, you will be brought to an upload page rather than the Media Library. This works the same as it did in WP 3.9
Automatic Height Adjustment/Sticky Toolbar: The 4.0 update did a couple of great things for the Page/Post Editor. It removed the scrollbar within the Page/Post Editor. Now, as you’re adding content, the editor will automatically adjust its height to your content. Don’t be worried about having to scroll back up to get to your toolbar to make adjustments. The toolbar is now sticky. As your content gets longer it will always be at the top of the page.
Video & Tweet Previews: The second thing 4.0 did to the Editor is made adding videos and tweets even easier. You can even preview them within the Editor. Instead of having to deal with searching for embed codes on YouTube, Vimeo, and Twitter, you can now simply paste in a URL to the Visual Editor, WordPress will works it’s magic, and a preview window will appear in the Editor. (P.S. You can even play the videos.)
Note: The live preview only works for certain sites as of right now – YouTube, Vimeo, and Twitter. To embed a Google Map, you still need to do the same process as before by pasting an embed code into the Text Editor.