Window.setClosable(boolean) doesn't work after upgrading to latest version

Vaadin 6 / 7 / 8 Framework UI
1

Hello,
I use window with spinner label to show the background activity. Unfortunatelly after migrating from 7.3.8 to 7.7.3, the x on the window is visible even if the setClosable(boolean) was called with false value:

[code]
public class Spinner extends Window {

private static final long serialVersionUID = -6360464010191183766L;

private final String HEIGHT = "10%";
private final String WIDTH = "10%";

public Spinner(){
    super();
    Label spinner = new Label();
    spinner.setSizeFull();
    spinner.addStyleName("spinner-label");
    spinner.addStyleName("spinner-window");
    
    VerticalLayout layout = new VerticalLayout();
    layout.setSizeFull();
    layout.addComponent(spinner);
    layout.setComponentAlignment(spinner, Alignment.MIDDLE_CENTER);
    
    setContent(layout);    
    center();
    setWidth(WIDTH);
    setHeight(HEIGHT);
    setClosable(false);
    setResizable(false);
    setDraggable(false);
    addStyleName("spinner-window");
}

}
[/code](see attached screenshot for result).

Is it bug? Or do I something wrong? Note, that with 7.3.8 the x was not visible.

Agata

28234.png