Is it possibe to preserve a flex tree component position with a client session using php or an alternative.

I have a flex tree component I am using as a menu to find specific products.  When the user double clicks their desired product they leave that page and they view the chosen products.  What I would like to happen is as long as their current session is active and they navigate back to the categories page the tree will stay in the position it was before they left rather than going back to it's default position.  The tree is being used with a php e-commerce driven site and all the shopping cart details are stored using the current session.  I have thought about making a pop up window instead so they root page stays on the tree, but I do not care for that. I would rather the position stay fixed until you close the session.