Java – vaadin create modal dialog window

How to in vaadin 7 Create modal dialog window in X? I have found that I have a main window and added it to my new dialog window, but how do I get the main window? I want to get it from the view

getApplication().getMainWindow()
getWindow()

They don't work

Solution

It depends on your major courses

public class MyApplication extends UI
{

    @Override
    protected void init(VaadinRequest request) 
    {
        addWindow(new ModalWindow());
    }
}