In Spring Rich parlance, a page refers to an implementation of org.springframework.richclient.application.ApplicationPage. Each ApplicationWindow will have one active ApplicationPage. The ApplicationPage refers to the area between the toolbar/menu and the status bar of the original application window.

I haven't dug in far enough to know if this ApplicationPage instance is used in other modal or non-modal windows

This sequence diagram picks up where the Kickstarting a Spring Rich Application sequence diagram invoked the showPage(String) method.

1. The Application.showPage(String) method takes a String parameter that contains the name of a bean in the application context. This bean name is an instance of org.springframework.richclient.application.PageDescriptor or org.springframework.richclient.application.ViewDescriptor. A PageDescriptor provides the metadata that describes a page. For example, the page's icon, title, description, etc. Some of these values are part of the visual representation of a page, such as icon and display name. The PageDescriptor also includes a method (buildInitialLayout) that is used to ....
2. At this point, the PageDescriptor bean is looked up in the application context using that text string that was initially passed in to the showPage method. If there is no bean found using the specified id value, an exception will be thrown.
3. An implementation of ApplicationPage coordinates the creation and operation of a GUI panel within the ApplicationWindow. Spring Rich contains a default implementation aptly named org.springframework.richclient.application.support.DefaultApplicationPage. Before this instance is used, a check of the application context is made (using the magic name "defaultApplicationPagePrototype") to see if the developer has provided an alternative. Note that the DefaultApplicationPage takes the ApplicationWindow and the PageDescriptor as parameters.
4. Before the initWindow method finishes, the main application window and all of its components will be created and made visible. A lot of activity happens in this method, and some of it is documented in the Kickstarting a Spring Rich Application sequence diagram.
   
   The createNewWindowControl creates a standard JFrame object and associates a handler to detect when the JFrame is closed.
5. The initWindowControl(JFrame) method calls several other methods that are responsible for decorating and positioning the JFrame. The applyStandardLayout method creates the menu, toolbar and status bar, and adds each of them to the application window. The applyStandardLayout method will require more detail and is covered in the ... sequence diagram. For now, know that all of the application window's content area is controlled by this method call. Finally, the prepareWindowForView method packs the window, sets its initial size and attempts to center the window on the screen.
6. Two lifecycle methods are fired. The first one is onWindowCreated and is unremarkable. The second lifecycle method is called showIntroComponentIfNecessary, and the framework will invoke the ApplicationLifeCycleAdvisor.showIntro() method if it hasn't yet been called.
7. The main application window is finally visible to the user. Another lifecycle callback method (onWindowOpened) fires on the ApplicationLifecycleAdvisor.
8. At this point, any listeners who have registered interest in the opening of a page are now notified.