In the previous chapter, we have seen how to layout the User Interface with XML and how to style it. We also looked into XHTML and several BTL widgets. Some of those widgets had interaction capabilities, as you may remember. These interaction capabilities are part of their implementation; we did not have to write a single line of code to enable this behavior. You could also see that the widgets we used had no real communication with each other. We were concentrating on their visual aspects. It is clear that we need more if we want to develop an interesting application.
In a real application, the interaction with the UI components triggers actions. For example, parts of the UI can be hidden or shown, or data can be visualized dynamically. Simply, interactions enable user work flow.
In the previous chapter, we never talked about what the web application looked like internally in the browser after the application XHTML document is loaded. We will see something...