1. A method comprising: at a computer system having one or more processors and memory storing one or more programs: sending messages in a first set of conversation messages for display; selecting, without user involvement, a second set of conversation messages by: comparing a topic for the first set of conversation messages with a second topic for the second set of conversation messages, or determining that the second set of conversation messages is similar to the first set of conversation messages; and sending messages in the selected set of conversation messages for concurrent display with the messages in the first set of conversation messages.