Simple Message Box is functionally the same as Message Box, except it doesn't subscribe to Timestamp messages.
The point of this demo is to create a working EventWeb client, with a minimum amount of development. Look at the source for SimpleMsgBox.html and SimpleMsgBox.js first when you're ready to create your own client.
You can also use this as a substitute for the regular Message Box if your browser disables it's pop-up mechanism.