Implementation of "New Messages" indicator in the main chat. The indicator shows up if the chat is not already scrolled to the bottom and goes away when the person scrolls.
Possible improvements:
the indicator goes away only when the person scrolls all the way to the bottom
clicking on the alert will make it disappear and scroll all the way to the bottom
move the NewMessages component out of the Chat.js file into its own file and have SimpleChat reference it (right now, it's defined in two places)
Implementation of "New Messages" indicator in the main chat. The indicator shows up if the chat is not already scrolled to the bottom and goes away when the person scrolls.
Possible improvements: