Add the ability to edit or delete messages that have been sent by the agent
Gitter.com has the same functionality and you can see people often use it to enhance or correct their answers/typo's.
Also the ability to completely delete a line would help very much.
Kevin Kingfisher commented
Simple, I make typos often and I find it useful to let agents edit their sent messages, and an option for the admin to let the end user to edit messages or not.
Cate Wheatley commented
If you make a mistake or reply to the wrong person when dealing with more than one chat at a time it would be good to be able to correct the mistake or delete the post to save on embarrassment!!
I would like to have an opportunity to edit text message once it is sent. Just like in skype, with a time and date of editing