This plugin allows you to add Twitter-like @reply links to comments. 
When clicked, those links insert the author name and a link to the comment you are replying to in the textarea.
Most of the code is taken from the Custom Smilies plugin by Quang Anh Do which is released under GNU GPL : 
https://wordpress.org/extend/plugins/custom-smilies/
Thanks to Guillaume Ringuenet for the arrow graphics.
I didn’t create anything new, and I do not claim so in any way. 
This plugin is just a feature I wanted and judging by the number of downloads I guess I wasn’t the only one. 😉

@ Reply

This plugin allows you to add Twitter-like @reply links to comments.

This plugin allows you to add Twitter-like @reply links to comments, including a preview of the comment replied to. 
When clicked, those links insert the author name and a link to the comment you are replying to in the textarea, and adds a Preview of the original comment to the @Reply (on hover using javascript).
This is a MASHUP of <a href="http://www.spreeblick.com/2007/09/25/worst-code-ever/" rel="nofollow ugc">this</a> and <a href="https://wordpress.org/extend/plugins/reply-to/" rel="ugc">that</a>
<h3>From the original README (Credits)</h3>
by <a href="https://wordpress.org/extend/plugins/profile/iyus/" rel="ugc">Yus</a>
Most of the code is taken from the Custom Smilies plugin by Quang Anh Do which is released under GNU GPL : 
http://onetruebrace.com/custom-smilies
Thanks to <a href="http://blog.guillaumeringuenet.info/" rel="nofollow ugc">Guillaume Ringuenet</a> who made the arrow graphics.
I didn’t create anything new, and I do not claim so in any way. 
This plugin is just a feature I wanted and thought it could interest some other people.

@Reply \w comment preview

This plugin allows you to add Twitter-like @reply links to comments, including a preview of the comment replied to. MASHUP of this: http://www.

@ Reply vs @Reply \w comment preview