Right now we only display a certain amount of messages and there is no way to show older messages. We should allow the user to load older messages.
Also, right now we're always loading 50 messages sent from user A to user B and 50 messages sent from user B to user A. This doesn't guarantee that we're loading the 100 more recent messages. If we want to load X messages, we should get X messages sent from A to B and X messages sent from B to A, sort them and then get the X more recent messages.