Add SealedNodes feature to Visject Surface nodes

Source/Editor/Surface/SurfaceNode.cs

@@ -390,6 +390,11 @@ namespace FlaxEditor.Surface
             UpdateBoxesTypes();
         }
 
+        /// <summary>
+        /// Array of nodes that are sealed to this node - sealed nodes are duplicated/copied/pasted/removed in a batch. Null if unused.
+        /// </summary>
+        public virtual SurfaceNode[] SealedNodes => null;
+
         /// <summary>
         /// Gets a value indicating whether this node uses dependent boxes.
         /// </summary>

Source/Editor/Surface/VisjectSurface.CopyPaste.cs

@@ -65,6 +65,25 @@ namespace FlaxEditor.Surface
                 return;
             }
 
+            // Collect sealed nodes to be copied as well
+            foreach (var control in selection.ToArray())
+            {
+                if (control is SurfaceNode node)
+                {
+                    var sealedNodes = node.SealedNodes;
+                    if (sealedNodes != null)
+                    {
+                        foreach (var sealedNode in sealedNodes)
+                        {
+                            if (sealedNode != null && !selection.Contains(sealedNode))
+                            {
+                                selection.Add(sealedNode);
+                            }
+                        }
+                    }
+                }
+            }
+
             var dataModel = new DataModel();
             var dataModelNodes = new List<DataModelNode>(selection.Count);
             var dataModelComments = new List<DataModelComment>();

Source/Editor/Surface/VisjectSurface.cs

@@ -749,7 +749,25 @@ namespace FlaxEditor.Surface
                     {
                         if (nodes == null)
                             nodes = new List<SurfaceNode>();
-                        nodes.Add(node);
+                        var sealedNodes = node.SealedNodes;
+                        if (sealedNodes != null)
+                        {
+                            foreach (var sealedNode in sealedNodes)
+                            {
+                                if (sealedNode != null)
+                                {
+                                    if (sealedNode.IsSelected)
+                                    {
+                                        selectionChanged = true;
+                                        sealedNode.IsSelected = false;
+                                    }
+                                    if (!nodes.Contains(sealedNode))
+                                        nodes.Add(sealedNode);
+                                }
+                            }
+                        }
+                        if (!nodes.Contains(node))
+                            nodes.Add(node);
                     }
                 }
                 else