How do I add a screen size definition to Android Studio?

I am building an Android application using Android Studio.

I want my layout to be as precise as possible, however, it seems that the list of Android virtual devices where we can render the layout to is limited to Nexus devices as shown in this screenshot below:

The "Generic Phones and Tablets" do not have much screen size and resolution variety, so I decided to add my device definition as such:

However, it did not appear in the devices that Android Studio can render a layout to in the design view of a layout.

The solution to this, is to restart Android Studio. The new devices should appear at the bottom of the list.