Only able to show one notification

I am using vaadin 7.5.0
I came across following issue.
Following code in servlet init method will create one button.
Click button once - a notification will show.
Click on notiication to close it
Click button again - vaadin hangs and I need to restart the tomcat server
Is this a bug?

protected void init(VaadinRequest request) {
    NativeButton button = new NativeButton("Show Notification");
    button.addClickListener(new Button.ClickListener() {
        public void buttonClick(ClickEvent event) {
  "Notification", "Voila!", Notification.Type.ERROR_MESSAGE);

That sounds very odd, notifications should work just fine like that. If you have push enabled for the UI, that sometimes has some issues with some browsers or browser versions.

Perhaps there’s some deployment problem, version incompatibility, or something. I hope your widget set and theme are compiled properly (see the ?debug window). If the entire Tomcat gets stuck, that sounds like some bigger deployment/incompatibility issue. Always first try cleaning up the Tomcat work state (especially when running under Eclipse) and restart.

Thanks Marko.

Howver I am sure it is not a problem on my side. If I create a menu item and put this code in menuitem, it works perfectly. Only when I launch this from a button, I run into this problem.
I provided code, you can try yourself