How to handle more application states of the same user with Vaadin 6

I have problem with stepping forward with our Vaadin 6 application. Do you know any way to properly handle more states of the application for the same user?

I mean for example we share URLs on social sites and those urls identify sort of states and user can visit these URLs but our problem when you open one state in one window and another state (another url) in other window, Vaadin6 will drop the firstly opened state because it stores them in the same session.

I've already found that Vaadin 7 could handle this in better way but we are in the middle of decision making how to go forward so I'm planning to measure all the possibilities with all the costs.

migrating from 6 to 7
tricking around with session management
... etc

I'd very appreciate if you could recommend some good way to deal with this issue.

Thank you, in advance, for all of your ideas.

Solution

I have same issue and resolve with help http://tobias-mattsson-magnolia.blogspot.ru/2012/05/vaadin-applications-and-tabbed-browsing.html

Full source code you can found here: http://pastie.org/3962656