Google deployed a full-screen mode for the New Compose in Gmail and it is now available  to users at LBL.

From Google's announcement ....

Key combinations:

Hold down Shift when you click the full-screen icon to pop the window out entirely. Holding Shift when you click Compose (or keyboard shortcut c) will also start a tear-off.

The formatting bar also shows by default now when you open compose in a new window or in a new tab (Ctrl+Compose or keyboard shortcut d).

Try it out

You can use it on an as-needed basis, or if you prefer, you can make it your default experience. To try it out:

1. Click Compose.

2. Click the double-arrow icon at the top right of the compose window.

3. Enjoy a larger composition mode that displays all of the formatting options by default.


  
 

If you want to make this option your default view, click into the options menu at the bottom right corner of compose and choose “Default to full-screen.” The next time you click Compose, you’ll be sent to this mode. Both types of compose can be minimized by clicking the black bar at the top.