How to re-arrange button onclick event in unity?

I guess I solve it right now.

Unity 2020.3.5f1

Apparently works with all UnityEvents because of the

 [CustomPropertyDrawer(typeof(UnityEventBase), true)] //includeChildren param
 

So it's applied to all subclasses of UnityEvent

Put this code inside an Editor folder.

 using UnityEditor;
 using UnityEditorInternal;
 using UnityEngine.Events;
 
     [CustomPropertyDrawer(typeof(UnityEventBase), true)]
     public class BaseCustomUnityEventDrawer : UnityEventDrawer
     {
         protected override void SetupReorderableList(ReorderableList list)
         {
             base.SetupReorderableList(list);
 
             list.draggable = true;
         }
     }

I really don't know why it's not a default.

Code explanation,

Using the UnityEventDrawer to hack in UnityEvent custom editor.

Before this, I had lots of headaches trying to redraw, add elements, etc to the UnityEvent inspector but I've got strange errors because of how UnityEvent draws in the inspector.

Couldn't do anything override OnGUI etc.

So while researching the drawer I found this ReorderableList field (draggable) and voilá!

https://github.com/vlab22/unityevent-reordering

Apparently we can't do this, and there's a technical reason why not. Apparently "internally this uses a delegate where call order is not defined" - there's more info and discussion about this here: https://forum.unity.com/threads/solved-unityevent-invoke-calling-order.265292/#post-1753393

I've seen the code myself, and it does have a very specific order. ...listeners shown in the inspector are called in the order shown first, then listeners added programmatically are called in the order they were added.

See @JoshuaMcKenzie answer that indicates there is a specific order here: Button On Click execution order?

If his answer is correct there should absolutely be functionality for re-arranging the event call order in the inspector.