code: protected void setupWindowHandlers() {
  
          registerHandler(Window.addResizeHandler(event -> setupCutOutPosition(focusElement, targetElement, cutOutPadding, circle)));
          registerHandler(Window.addWindowScrollHandler(event -> setupCutOutPosition(focusElement, targetElement, cutOutPadding, circle)));
      }
docs: Configures a resize handler and a scroll handler on the window to
  properly adjust the Cut Out.