code: public void close() {
          // Turn back the cursor to POINTER
          RootPanel.get().getElement().getStyle().setCursor(Style.Cursor.DEFAULT);
  
          windowCount--;
          if (closeAnimation == null) {
              getOpenMixin().setOn(false);
              if(windowOverlay != null && windowOverlay.isAttached() && windowCount < 1) {
                  windowOverlay.removeFromParent();
              }
              CloseEvent.fire(this, false);
          } else {
              closeAnimation.animate(this, () -> {
                  getOpenMixin().setOn(false);
                  if(windowOverlay != null && windowOverlay.isAttached() && windowCount < 1) {
                      windowOverlay.removeFromParent();
                  }
                  CloseEvent.fire(this, false);
              });
          }
      }
docs: Close the window.