As you can see, I am writing an email in Gmail without the standard Inbox in the background. This is a nice hack if you want to send an email without unintentionally glimpse your full inbox. To achieve this simple use the following url:
To do this easily, simple bookmark the page and use that bookmark whenever you want a distraction free email composition with Gmail. PS: After sending you email you can write a new one by simply refreshing your page. Happy Emailing — Sincerely Yours, Ibrahim 
Tip from a reader (Marc): If you want a similar solution when replying to a email, simply pop-out the reply window then clicking the double-arrow icon in the upper right corner while pressing the shit key as shown in the images below.
An easier keyboard-based solution is Shift+r.
Ibrahim El Merehbi 