Fusiondirectory does not manage well browser using tabs.
It is not possible with FD to edit different object using the option : "Open in a different Tab".
Here is an example : I want to compare both users at the same time foo and bar. I go on the user list and I want to edit foo in one tab and bar into another tab. So I use my center click to open the both users in two different tabs => Only the foo user is displayed in the both tabs.
FD should be aware to edit / view ANY object (Not only users) in different browser tabs.