You often use the "Reply All" button in group communication. At that time, it may seem convenient, though it may be distressing later one, when different recipients start reverting on it, even when you don't expect. No matter how many times you delete these messages from your inbox, the next message in the chain will make it all come flashing back.
On clicking Gmail's "Compose" button, a window appears in the right corner of the screen. Well, this window has new options now. In the top-right corner of that "Compose" window, you will find three icons: Minimize, Full-screen and Close. By clicking the one in middle, window gets enlarged.