How to use a keyboard shortcut for display mirroring in Mac OS High Sierra

If you use an external display with your Mac laptop, you can use Command-F1 to turn display mirroring on and off in macOS High Sierra.  Display mirroring is when your external monitor and laptop display show the same screen.

Mirror Displays.jpg

If you need to temporarily see your Dock or your open windows on both displays, Command-F1 lets you accomplish this. It’s a shortcut to the System Preferences > Displays > Arrangement > Mirror Displays command.