Change Excel behaviour in Citrix session for Cognos Controller

IBM Cognos Controller 10.1
Windows 2008 server/Citrix Server for Controller Client
Microsoft Excel 2007

When user inside Cognos Controller click on Reports - Run, Microsoft Excel pop's up and placed Excel spreadsheet in front of Cognos Controller.
This is irritating in a Citrix session, because it is difficult to switch back to Controller window.

On the Citrix Server (Windows 2008 server) for the Cognos Controller client, you need to look into registry value below and change values for Excel to change this behavior.

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Terminal Server\Install\Software\Microsoft\Office\12.0\Excel

If possible copy the registry values from a working Citrix server to your server

What exact registry needs to be changes ? Thanks.