Microsoft Office 4.2.1: Command-Option-Tab Switches Apps

I just installed System 7.5 and Microsoft Office 4.2.1 and I notice that hitting the Command-Option-Tab key combination switches between applications.

Where did this feature come from?
Microsoft Office installs a Control Panel with an option called QUICKSWITCH that allows you to do this-it can be toggled on or off.
Published Date: Feb 19, 2012