Gerber Viewers are great for viewing your PCB manufacturing files. Each file is assigned a color (like:Green, Red, Yellow, and Blue) and then hundreds of line, circles, and various shapes are displayed onto the screen. This is perfectly fine for CAM experts, but have you ever wanted to see "exactly" what your final PCB looked like before it was manufactured.
When you can truly see a PCB in it's finished form, it becomes much easier on the eye to "catch mistakes".
This tutorial demonstrate hows to perform realistic PCB Preview, View Nets, and checkout Panel NC Routs\Tabs.
Important: Make sure to have a border layer present. If not FAB 3000 will detect and create one for you.