title: Multiple tabs on same session scoped bean are interfering each other
body: <p>I have JSF 2.0 e-commerce application. I'm using 2 session scoped beans: ProductBean and CartBean.
  ProductBean holds Product entity representing current product user is viewing. CartBean holds list of Products.
  CartBean has method addProduct(Product p). I have problem with adding to cart when using multiple tabs. Here's scenario:</p>
  
  <blockquote>
    <ol>
    <li>User visits product page: /product?id=111</li>
    <li>User opens new browser tab for another product: /product?id=222</li>
    <li>User goes back to first tab and clicks 'add to cart' - Second product (id=222) is added to cart.</li>
    </ol>
  </blockquote>
  
  <p>Here's the code of add to cart commandButton action:</p>
  
  <pre><code>#{cartBean.addProduct(productBean.product)}
  </code></pre>
  
  <p>It's clear to me what's going on. How can I make this work on multiple tabs?</p>