Show time of message seen by other person
Add a feature which shows when other person had seen your's message.
This is already a feature on Skype 8.35. When someone reads your message, as long as they are not marked as 'invisible', you will receive a read receipt, informing you that they have read your message. If you click on that read receipt (a little icon of them to the right of the message they have read), it will show when they read it.