Made it so the visuals of dragging an actor will only show between the nodes and on the node.

Source/Editor/GUI/Tree/Tree.cs

@@ -40,6 +40,11 @@ namespace FlaxEditor.GUI.Tree
         private Margin _margin;
         private bool _autoSize = true;
 
+        /// <summary>
+        /// The TreeNode that is being dragged over. This could have a value when not dragging.
+        /// </summary>
+        public TreeNode DraggedOverNode = null;
+
         /// <summary>
         /// Action fired when tree nodes selection gets changed.
         /// </summary>