[horde] Can't start a second horde session?

[Kevin Konowalec]

Using Horde 3.1.2.  Here's the scenario:  You open up a browser  
window and go to https://www.myserver.com/.  Imp has been set as the  
initial Horde application and the webroots for horde and imp are set  
to '/horde/ and ' ' respectively in horde/config/registry.php.  You  
get to the login page and can login as usual.  You then open a second  
browser window and go to the same URL.  Only this time the URL  
immediately redirects to https://www.myserver.com/mailbox.php? 
page=1.  Interestingly enough it seems to not be in the same frameset  
as the sidebar is not on the page with the second instance at all.

This is unexpected behavior as the older version I had been running  
would bring you back to the login page and let you start another  
session (perhaps using a different ID... some of our users are  
responsible for several different email accounts and like each one in  
a different browser window).  Ultimately it doesn't make a lot of  
sense to be able to hijack a session just by opening another instance  
of the browser.

Has something changed in the latest version of Horde to prevent  
multiple sessions on one machine?  If not, what can be done to  
prevent this behavior?