Fix compilation issues in Unity 6.5 for the Tab functionality; make sure to create 'empty' instance when using + button in the ReordableList

Author: arimger

Assets/Editor Toolbox/Editor/Drawers/Toolbox/Decorator/BeginTabGroupAttributeDrawer.cs

@@ -506,18 +506,38 @@ private struct GroupData
 
         private struct ContextKey : IEquatable<ContextKey>
         {
-            public int InstanceId;
             public string GroupId;
+#if UNITY_6000_4_OR_NEWER
+            public EntityId InstanceId;
+#else
+            public int InstanceId;
+#endif
 
-            public bool Equals(ContextKey other) =>
+#if UNITY_6000_4_OR_NEWER
+            public readonly bool Equals(ContextKey other)
+            {
+                return InstanceId == other.InstanceId && GroupId == other.GroupId;
+            }
+
+            public override readonly int GetHashCode()
+            {
+                return HashCode.Combine(GroupId, InstanceId);
+            }
+#else
+            public readonly bool Equals(ContextKey other) =>
                 InstanceId == other.InstanceId && GroupId == other.GroupId;
 
-            public override int GetHashCode() =>
+            public override readonly int GetHashCode() =>
                 (InstanceId * 397) ^ (GroupId != null ? GroupId.GetHashCode() : 0);
+#endif
         }
 
         private static readonly Dictionary<ContextKey, Type> ContextCache = new();
+#if UNITY_6000_4_OR_NEWER
+        private static EntityId _lastSelectionId = EntityId.None;
+#else
         private static int _lastSelectionId = -1;
+#endif
 
         static TabDiscovery()
         {
@@ -527,7 +547,11 @@ static TabDiscovery()
         private static void ClearContextCache()
         {
             ContextCache.Clear();
+#if UNITY_6000_4_OR_NEWER
+            _lastSelectionId = EntityId.None;
+#else
             _lastSelectionId = -1;
+#endif
         }
 
         public static Type GetContextType(string groupId)
@@ -536,7 +560,11 @@ public static Type GetContextType(string groupId)
             if (target == null)
                 return null;
 
+#if UNITY_6000_4_OR_NEWER
+            EntityId instanceId = target.GetEntityId();
+#else
             int instanceId = target.GetInstanceID();
+#endif
 
             if (_lastSelectionId != instanceId)
             {

Assets/Editor Toolbox/Editor/Internal/ReorderableListBase.cs

@@ -461,18 +461,23 @@ public void AppendElement()
             Size.intValue = newSize;
             Index = newSize - 1;
 
-            if (overrideNewElementCallback == null)
+            List.serializedObject.ApplyModifiedProperties();
+            var property = List.GetArrayElementAtIndex(Index);
+            var fieldInfo = property.GetFieldInfo();
+            if (fieldInfo == null)
             {
                 return;
             }
 
-            //make sure serialized data is up-to-date
-            List.serializedObject.ApplyModifiedProperties();
-            var property = List.GetArrayElementAtIndex(Index);
-            var newValue = overrideNewElementCallback(Index);
-            //update property directly by the reflection
-            var fieldInfo = property.GetFieldInfo();
-            property.SetProperValue(fieldInfo, newValue, false);
+            if (overrideNewElementCallback != null)
+            {
+                var newValue = overrideNewElementCallback(Index);
+                property.SetProperValue(fieldInfo, newValue, false);
+            }
+            else
+            {
+                property.SetProperValue(fieldInfo, null, false);
+            }
         }
 
         public void RemoveElement()