This script creates a Markdown toolbar whenever you make/edit text posts or comments in reddit.com.

It offers:

• Common formatting buttons.
• CODE markdown button that wraps selected text in ` or ``` if multiple lines are selected.

Tested on FF+Greasemonkey.

This is a modified version of this script Markdown toolbar for GreasyFork and UserStyles.org .
Thanks a lot to wOxxOm for making that script.