There are a few ways to make the reply box look like the compose box, so you can open other messages or use Gmail's search feature while replying to a mail.
1. Shift-click the "reply" link or the entire box that includes the message "Click here to Reply or Forward". You can also Shift+click "forward" to open the forwarded message in a pop-out box.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi43JPWAbP8s7z1Y0WhRxJRCdJEIQk9TQrkSqoWwxQfGq7q7xU2YK7XVYyAT2B-mzosOVNJoLxQD5xwqyPkS7gXsbnrrUjxb1nOGyFR5jwYgDjDRZpiN2HRVaXzKgIV7UNU7C17q9aeS0Ow/s640/gmail-reply-link.png)
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSmvBcshGiUqAr6VLmZ1uidw63fevfTBdc-OVoc5-n86jhKCmzcnSVd0cc2TXoSeuiZkXDxSE162GqX-iFwb6yYe9y995oEDcwc3OXAPI9qHQHkQmQ2TkfZ9tJzYoq2RK6zu8L5cWzVroc/s640/gmail-reply-separate-box.png)
2. Use keyboard shortcuts: Shift+r to reply in a pop-out box, Shift+a to reply to all, Shift+f to forward in a pop-out box.
3. If you've already writing the reply, click the arrow above your reply and pick "Pop out reply".
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLZxjAGQ5nAkkC-27NjUxwluwZFoii6USexDBZRSD8QMMswm3prEnc7bbJl-c81TQSrfZDR6qHBq8FtSIJkZuGr9WPkLc2r_zG0Qdf8UN8EycasEMYrX7FuY9wVcXtu924a0QIR8RERolF/s640/gmail-reply-pop-out.png)
To go back to the regular interface, minimize the compose box, find this message "You are currently editing your reply in a separate window" and click "Show your draft here."