This video shows us the method to use iPad as a touchscreen monitor for your Mac. You have to use iDisplay available on app store. Start the application on your iPad and Mac. Tap the server on your iPad and on the Mac click 'Confirm' to connect it to iPad. Hit 'OK' on iPad. Now you can open a window on the Mac. You can drag the window out of the Mac screen on to the iPad. Now it will act as a touch screen. You can use all the touch screen features of iPad for this window. You can drag the window back to your Mac using the mouse. This finishes the video.