Duplicate Windows visually copies any window in OS X live and on-the-fly. It’s like display mirroring for individual windows!

• Duplicate any window. Select any window on your Mac, and get an instant resizable copy that stays up to date with the original.
• Monitor anything. Don't disrupt your workflow. Watch videos. Watch a sports game. Monitor your servers. Keep an eye on any window you like. Just duplicate it, tell it to stay on top, resize it to just how you want it and get on with your work.
• Presenter Mode for any software. You can duplicate windows across monitors. Drive a software demo with your notes right along side on your laptop screen, while only projecting the software you're demoing. You can even duplicate as many windows as you want.