Turn off MacBook Pro's display while connected to external monitor on Yosemite How do you turn off the MacBook Pro’s display with the lid open while using an external monitor on Mac OS X 10.10 Yosemite?

All the previous methods—such as the one’s listed here—that have worked on Mavericks no longer work on Yosemite.

Does anyone know the way to do this on Mac OS X 10.10 Yosemite? Turning down the brightness is not the same as turning off the display as the GPU still sends a signal to the internal display and the external monitor.

These were the terminal commands to achieve this on Mavericks:

Enable

sudo nvram boot-args="iog=0x0"

Disable

sudo nvram -d boot-args

Anyone know how to achieve this on Yosemite?
Found this wonderful free application :

https://github.com/Eun/DisableMonitor/

Works like a charm.