MeshRendererOrderInLayerPropertyField.cs

using UnityEditor;
using UnityEngine;

namespace Kogane.Internal
{
    [InitializeOnLoad]
    internal static class MeshRendererOrderInLayerPropertyField
    {
        static MeshRendererOrderInLayerPropertyField()
        {
            _ = new EditorGUIUtility.PropertyCallbackScope( Callback );

            static void Callback
            (
                Rect               rect,
                SerializedProperty serializedProperty
            )
            {
                var serializedObject = serializedProperty.serializedObject;

                if ( serializedObject.targetObject.GetType().Name != nameof( MeshRenderer ) ) return;
                if ( serializedProperty.propertyPath != "m_DynamicOccludee" ) return;

                var sortingOrderProperty = serializedObject.FindProperty( "m_SortingOrder" );
                sortingOrderProperty.intValue = EditorGUILayout.IntField( "Order in Layer", sortingOrderProperty.intValue );
            }
        }
    }
}