Help understanding Vaadin sampler application

I am trying to figure out how the Vaadin Sampler application is set up such that is appears as if there is an HTML page for each component that is displayed. For instance if i click on ‘Tooltips’ the following URL is called on the browser’s navogation bar http://localhost:8888/sampler/#Components/Common/Tooltips

if i click on ‘Icons’ the following is the URL http://localhost:8888/sampler/#Components/Common/Icons

When i create a sample application the URL is always constant. So what is the Vaadin Sampler doing differently that it shows multiple URLs and HTML pages ?

There is an invisible component, called URIFragmentUtility. Add it to a window or layout (it is not visible to the user) and register a fragment change listener with it. This component tracks the URI changes (text after # character) and invokes your listener. The reverse way is to change fragment from the URIFragmentUtility by calling setFragment method.