Once you become a Messages addict, you often wind up with multiple chats in progress. These days, Messages contains all your conversations in a single window, as shown in Figure 20-9.
You can press Control-Tab to switch from chat to chat in a multi-chat window. Add the Shift key to move the other way.
Figure 20-9. Messages keeps tabs on your various simultaneous conversations—literally. Click the different tabs to switch chats. Double-click one to open it into its own window, without the tabs taking up space.