How to make class that extends generated class implements View become a win

Hi , Good Day Experts!

I have a Question : How to make class that extends generated class implements View become a Windows view?
Here is my Code, I used vaadin designer to generate my design html , then I have Generated Class and Subclass View:

I have Four classes :-
a) CustomerForm.java ( Generated class from vaadin designer)
b) CustomerFormView.java ( subclass controller)
c) CustomerSearch.java ( Generated class from vaadin designer)
d) CustomerSearchView.java ( Subclass controller to search)

1. First of all, i wanted to add a function from class CustomerSearchView.java where User will click a button Update and will load a windows from class CustomerView.java as a form with update , how to make a class that extends view can be Windows?

1.1. CustomerSearchView.java

HorizontalLayout horizon= new HorizontalLayout();
            Button updateCustomer= new Button(new ThemeResource("../sample/img/updateCust.gif"));
           updateCustomer.addStyleName("nobackgroundTable");

 updateCustomer.setDescription("Edit Customer");
            demo.addClickListener(new ClickListener() {                
                @Override
                public void buttonClick(ClickEvent event) {
                     Notification.show("Edit user");
                     CustomerFormView.open((Customer)itemId, false);
                }
            });

2. CustomerFormView.java

....
public class CustomerFormView extends CustomerForm implements View {

// constructor
@SuppressWarnings("serial")
    public CustomerFormView(final Customers customer,final boolean preferencesTabOpen) {
    // my controller to add data to forms.
}
public static void open(final Customers customer, final boolean preferencesTabActive) {
     DashboardEventBus.post(new CloseOpenWindowsEvent());
            Windows w =new CustomerFormView(customer, preferencesTabActive);
           UI.getCurrent().addWindow(w);
            w.focus();
        }

Error Occurred at this line  :
 

Window w =new PatientRegistrationView(person, preferencesTabActive);
           UI.getCurrent().addWindow(w);

errors description:
Multiple markers at this line
    - Type mismatch: cannot convert from CustomerFormView to
     Window
    - Line breakpoint:CustomerFormView [line: 791] - open(Customer,
     boolean)

Anyone have Idea to solve this problem , add the Window page.

Good Day Johannes ,

Its work fine, Thank You very much for the solutions.