把底层再分割一下

AIStudio.Wpf.DiagramApp/ViewModels/LogicalViewModel.cs

@@ -119,7 +119,7 @@ namespace AIStudio.Wpf.Logical
             RaisePropertyChanged("Items");
         }
 
-        protected override bool AddVerify(SelectableViewModelBase arg)
+        protected override bool AddVerify(SelectableDesignerItemViewModelBase arg)
         {
             if (base.AddVerify(arg) == false)
                 return false;