Three displays: two stacked, two mirrored

At the moment my display setup consists of two 24″ monitors stacked vertically. Today I had a visitor and wanted to show stuff across my office desk and found the following gem regarding multiple display setups (from the Display Settings Help):

If more than two displays are connected to your Mac, you can specify that some are mirrored displays and others show the extended desktop. For example, if you have three displays, you can have two displays showing the same information and the third display showing the extended desktop.

  1. Set up all the displays as an extended desktop.
  2. Option-drag a display icon onto another display icon to mirror those two displays.

So now I could continue with my regular setup, but flip open the lid of my Macbook and use it show stuff to my visitor!

Three displays, two stacked, two mirrored
Three displays: two stacked external¬†displays with the¬†lower external display mirrored to the built in display of my Macbook 15″