This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Yes. They are doing different things and just happen to live on the same page. For example, suppose I have buttons for "add" and "delete." These do different things and are going to have different sequence diagrams.