So now you can edit your previous message.
Just imagine, after you typed a message you saw a typo? The only way before was just send another message with correct text. Now you can just click Up arrow on your keyboard and it will replace text area with previous message where you can edit it and send it again.
Just the same thing as skype does. Same functionality is enabled to client part. You can edit only your last message.
Screenshot
For update just replace files from master branch and clear cache.
Developing application takes a lot of time. You can support application by donating. There is no company behind this application and it takes away my free time. Every donation matters and does not matter how small it is!