Twitter rolled out a new user interface to their Chrome app for TweetDeck. The app is still not a packaged app so it runs inside the browser. Hopefully Twitter developers would eventually convert this into a Chrome Packaged App so that it can run independently of the browser.
The new update has the top bar moved to the left side. The company said:
In line with Twitter’s own design aesthetic, this update delivers a lighter and simpler TweetDeck design. We moved the top bar to the side, and created some significant usability improvements around column reordering and easier navigation.