How to know which drawable resource is selected

I am using Android Studio 1.2.1.1. When editing an xml layout file such as "\large-hdpi\my-layout.xml", a preview is generated in the right hand panel. In this case I have the Nexus 7 selected which is 800x1280. I expect the layout to be "large-hdpi" which it is, and I expect "hdpi" drawables to be used which it are not. The problem is, I see no way to find out exactly which drawable resource folder is being used for the preview. Sorry if it's obvious but I just don't see it.