Handling login and multiple browser tabs

Hi,

I just created an Vaadin 7 application with login functionallity with this tutorial:
https://vaadin.com/wiki/-/wiki/Main/Handling%20logins

In generall it works fine. But if I click on a link and choose ‘open in a new tab’ in my browser, I have to login again in my application.

How can I avoid this second login in a new browser tab?

Julian