Matrox PowerDesk-HF > Main interface > Matrox Zoom > Multi-Display Zoom
Select the region you want to appear full-screen on another display.
After you click this, your mouse pointer changes and you can select a region. To select a region, drag your mouse pointer over an area in your display. You can press [Esc] to cancel.
If you select a zoom region that doesn't have the same aspect ratio (width and height proportion) as your other display, the region appearing on your other display won't fill the screen. To force a zoom region you select to use the same aspect ratio as your other display, press and hold [Ctrl] while selecting a region.