How would I duplicate this? I’m creating a custom inspector and for simplicity’s sake I want to be able to drag my armor components onto targets on the player.
Well, the Avatar editor is a quite huge thing. Just see for yourself. Download ILSpy and open the UnityEditor.dll assembly found in your Unity installation folder "\Unity\Editor\Data\Managed".
The class that is most likely responsible for drawing and handling the Avatar mask is the “AvatarSkeletonDrawer” class. However the whole Avatar editor is made up by 15 classes. It consists of several modules for the different edit modes. The class “AvatarEditor” is the actual custom inspector for the Avatar object. The “AvatarControl” class has a nested “Styles” class which seem to hold quite a few GUIStyle icon references.
I don’t think you’ll get any more specific answers about that topic ^^. For reference here’s my OnGUI crash course.