Google Updates Gmail, Now with Full Screen Composition
It’s a welcome change. Currently, you must write your email messages in a window down off to the side of the screen, which doesn’t really make a lot of sense. With this update, the compose window will be centered, and you can expand it to be as large as your screen can handle. Google also says that the formatting toolbar is now on by default.
If you wish to make the full screen compose option automatic, you can do so by clicking the arrow (technically, the “More” menu) at the bottom right of the window by the trash can icon and selecting “Default to full-screen”.
Google is rolling the change out to users over the next couple of days.