If you click on the round information i button at the right upper corner of that chart, you will get a description of how they have done this.
They made use of the new feature 'conditional enablement of expressions and dimensions', check the dimension tab and expression tab for the new entry field where you can enter the conditional.
It's best if you open the what's new app in the desktop client and look at the properties.
Hope this helps,
The What's New demo is a good start. You might want to check out an article here that gives some detail about how to do this as well: http://livingqlikview.blogspot.com under the heading Conditional Dimensions and Expressions - Tips and Tricks