Creating a new application-level window is much like creating a child window, except that the window is added with addWindow() to the application object instead of the main window.

public class WindowTestApplication extends Application {
    public void init() {
        final Window main = new Window ("Window Test Application");
        setMainWindow(main);
         
        /* Create a new window. */
        final Window mywindow = new Window("Second Window");
        
        /* Manually set the name of the window. */
        mywindow.setName("mywindow");
        
        /* Add some content to the window. */
        mywindow.addComponent(new Label("This is a second window."));

        /* Add the window to the application. */
        addWindow(mywindow);
    }
}

This creates the window object that a user can view by opening the URL in a browser. Creating a application-level window object does not open a new browser window automatically to view the object, but if you wish to open one, you have to do it explicitly as shown below. An application-level window has a unique URL, which is based on the application URL and the name of the window given with the setName() method. For example, if the application URL is http://localhost:8080/myapp/ and the window name is mywindow, the URL for the window will be http://localhost:8080/myapp/mywindow/. If the name of a window is not explicitly set with setName(), an automatically generated name will be used. The name can be retrieved with the getName() method and the entire URL with getURL().

There are three typical ways to open a new window: using the open() method of Window class, a Link, or referencing it from HTML or JavaScript code written inside a Label component.

The Window open() method takes a resource to open and the target. You can use ExternalResource to open a specific URL, which you get from the window to be opened with the getURL() method.

/* Create a button to open a new window. */
main.addComponent(new Button("Click to open new window",
                  new Button.ClickListener() { 
    public void buttonClick(ClickEvent event) {
        // Open the window.
        main.open(new ExternalResource(mywindow.getURL()), "_new");
    }      
}));

The target name is one of the HTML target names. How the window is exactly opened depends on the browser. Browsers that support tabbed browsing can open the window in another tab, depending on the browser settings.

Another typical way to open windows is to use a Link component with the window URL as an ExternalResource.

/* Add a link to the second window. */
Link link = new Link("Click to open second window",
                     new ExternalResource(mywindow.getURL()));
link.setTargetName("second");
link.setTargetHeight(300);
link.setTargetWidth(300);
link.setTargetBorder(Link.TARGET_BORDER_DEFAULT);
main.addComponent(link);

Using a Link allows you to specify parameters for the window that opens by clicking on the link. Above, we set the dimensions of the window and specify what window controls the window should contain. The Link.TARGET_BORDER_DEFAULT specifies to use the default, which includes most of the usual window controls, such as the menu, toolbar, and status bar.

Another way to allow the user to open a window is to insert the URL in HTML code inside a Label. This allows even more flexibility in specifying how the window should be opened.

/* Add the link manually inside a Label. */
main.addComponent(new Label("Second window: <a href='"
                            + mywindow.getURL() + "' target='second'>click to open</a>",
                  Label.CONTENT_XHTML));
main.addComponent(new Label("The second window can be accessed through URL: "
                            + mywindow.getURL()));

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