UIElement debugger - what is it for?

I did a small test and don't see it in the debugger. Is it only for editor GUI?

Code (CSharp):

1. public class UITester : MonoBehaviour
2. {
3.     void OnGUI()
4.     {
5.         GUI.Label(new Rect(10,10,50,50),  "test");
6.     }
7. }

 

I guess, it's not for the old IMGUI, but their new retained-mode UI system only?

https://docs.unity3d.com/Manual/UIElements.html

 

Still experimental I see, hopefully it'll be available at runtime.

 

When working with UIElements, it became my best friend immediately! It helps you visualize the hierarchy tree and the properties and USS files applied to each element. It's great.