The Multi-Window toolbar enables the ability to work in multiple windows simultaneously. For example, you may wish to browse a website in one window while opening a second window to take notes in the Promethean Whiteboard App. When you see the Multi-Window toolbar at the bottom of a window, this indicates Multi-Window capabilities are in effect.
Please note that Multi-Window is only available on the ActivPanel Titanium.
Watch this short video to learn more about utilizing Multi-Window: