title: built in way to identify each browser window
body: <p>IS there, a cross browser, way to identify each browser window uniquely?<br>
  I need to store some values which are unique for a window.<br>
  Even if the user opens two windows on the same browser to the same site.  </p>
  
  <p>There is no Ajax involved, every click on a link will load a new page.</p>
  
  <p>And how would I access that name from the server? (for this, assume I use php, but example in any other language, is also good)</p>