We’ve added Twitter preview functionality to our compose window. Now, in addition to seeing the metadata (image/link/title/description), you will see a preview of how your content will look when posted to Twitter.
When posting to Twitter and Facebook simultaneously, you’ll see both previews of the post on both social networks. This functionality is available for image, link (Twitter cards), multiple-image posts and video. Use the computer and mobile icons to toggle between both mobile and desktop previews.
This new view will automatically populate when you are composing Twitter messages; no other action is needed from you to start viewing post previews!