How to determine the readability of chat messages?

Question

Ruby on Rails

There is a prelude reminiscent of Google Talk. Those. chat between two users. How can you tell if a message has been read by a user? Messages are simply displayed, you don't need to click anywhere, they say you read or didn't read, as in letters. And how then?
So far, I tend to think that the logic is something like this:
- The user opens a window and all the messages that are - become read
- Until the user has opened the window - the messages are not read.
Those. tie only on open or closed window. But maybe there are more interesting ways?

Answer 1

Can be by hover
Can be by scroll
Can be by visual contact (if you downloaded a long conversation from your mobile, it's not a fact that everything will be on the screen right away?)
By the ratio of time on the page to the number of characters in new messages
At the beginning of writing the answer