When editing a property that expects a resource reference, the ADT brings up the "Resource Chooser", which shows the available resources in the project. In addition to picking among existing resources, you could also create a new resource - provided that resource was of type String.
That restriction has now been removed and you can create new resources of any value type. After choosing a name and a value, the ADT will edit the existing value XML files on your behalf, or create a new one if necessary. It will follow the convention that it places resources in an XML file of the same plural name as the type - strings.xml for a @string, integers.xml for an @integer, and so on.