Double click lead to page dead~

hello,every one,i found a problem that ,i create a popup window with a button to close the window.
when double click the button on the window quickly,the page will dead.

code:

@Override
protected void init(VaadinRequest request) {

    final VerticalLayout layout = new VerticalLayout();
    layout.setMargin(true);
    setContent(layout);

    Button btn = new Button();

//

    btn.addClickListener(new ClickListener() {

        @Override
        public void buttonClick(ClickEvent event) {
            VerticalLayout layout = new VerticalLayout();
            Button btn2 = new Button();
            layout.addComponent(btn2);
            
            Window window = new Window("test", layout);

// window.setDraggable(false);
V7UI.this.addWindow(window);
window.center();
btn2.addClickListener(new ClickListener() {

                @Override
                public void buttonClick(ClickEvent event) {
                    window.close();
                }
            });
            window.bringToFront();
        }
    });
    layout.addComponent(btn);
}

i found this is because when i double click the button ,vaadin will think as i will drag the window , so that the method

private void beginMovingWindow(Event event) {
if (draggable) {
showDraggingCurtain();
dragging = true;
startX = WidgetUtil.getTouchOrMouseClientX(event);
startY = WidgetUtil.getTouchOrMouseClientY(event);
origX = DOM.getAbsoluteLeft(getElement());
origY = DOM.getAbsoluteTop(getElement());
DOM.setCapture(getElement());
DOM.eventPreventDefault(event);
}
}

of Class VWindow will be called ,will create a DIV draggingCurtain,which cause the problem,how do i solve or avoid this problem,thank you very much,forgive my poor english