Since this menu item is going to load a layout, it is best to start by opening or designating a window to place the contents within.
The 'pageWindow' element allows us to open a new window or load a layout into an existing window within the Technology Explorer.
A window is any tab or floating object you see with a title bar. What truly defines a window element are the controls to navigate forward and backward, and to reload the current page.
The attribute 'target' indicates which window to load the content into. There are three reserved names you should know about; '_active' will load the contents into whatever window is selected on the default stage, '_blank' will open a new window on the default stage, and '_self' will open the link in the current calling window. '_self' should not be used in menu items. If a window of the given name exists within a stage, that page will be loaded into that window; however, if the name does not exist a new window will be created.
Stages are locations that can contain windows. You can direct a page to a given stage using the attribute 'windowStage'.
Simply put, a stage is an area that can contain windows. By default there are two stages you can use; the 'defaultStage' which is the stage this tutorial is loaded into and the 'floatingStage' that contains floating windows. There is also a third stage loaded called the 'SuperStage' in which all of the Technology Explorer content is loaded into. You should NEVER send content to this stage.
As an aside there is a stage loaded in the right panel of the tutorial that is the default stage for tutorial content. A stage is also used in the bottom panel of the Ad Hoc query to display the results within.
You will learn more about creating a stage in part '3. Stages' of this tutorial.