The good news is you can use your laptop as a second screen for your main computer, and you don't even need a third-party app ...
Starting with Windows 8, the Wireless Display Adapter (WDA) lets a Miracast-enabled Windows PC, tablet or phone mirror its screen on the connected screen via Wi-Fi. Starting with the Anniversary ...
Open Settings Select System settings Open Display settings Scroll down till you see Multiple Displays Locate Connect to a wireless display ... stream or duplicate my Windows computer on to Xbox ...