Use the ribbon button to cause the application to fill all your screens available. If you have only one monitor, it will just maximize to that screen.
Everyone here at my company that likes to work across multiple screens has found this tool to be very useful. Working on large building systems projects in 3D, it is often very useful to see what you’re working on in multiple views simultaneously.
Previously we were using the NVidia NView application to do this for us, but it occasionally just stops working. We also got some new workstations with ATI cards in them, and their application doesn't work the same. Now we get consistent multi-monitor spanning very easily within the application.
In version 2 I have added a new support command SplitAtScreen that will split your model space into viewports with their edges aligned to the edge of your physical monitors.
And now it's free! Enjoy.