Revert "Revert "block 可以拖拽到内部，还有少量问题待解决""

This reverts commit fcd7beb193.

AIStudio.Wpf.DiagramDesigner/ViewModels/DefaultViewModel/BlockContainDesignerItemViewModel.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using AIStudio.Wpf.DiagramDesigner.Models;
+
+namespace AIStudio.Wpf.DiagramDesigner
+{
+    public class BlockContainDesignerItemViewModel : BlockDesignerItemViewModel
+    {
+        public BlockContainDesignerItemViewModel()
+        {
+        }
+
+        public BlockContainDesignerItemViewModel(IDiagramViewModel root) : base(root)
+        {
+        }
+
+        public BlockContainDesignerItemViewModel(IDiagramViewModel root, SelectableItemBase designer) : base(root, designer)
+        {
+        }
+
+        public BlockContainDesignerItemViewModel(IDiagramViewModel root, SerializableItem serializableItem, string serializableType) : base(root, serializableItem, serializableType)
+        {
+        }
+
+        protected override void InitNew()
+        {
+            base.InitNew();
+
+            Contains.Add(new ItemsContainerInfo(this.Root, this));
+        }
+
+        public override void AddChild(BlockDesignerItemViewModel child)
+        {
+            var oldchildren = FirstContain.Children.FirstOrDefault();
+            if (oldchildren != null)
+            {
+                this.RemoveChild(oldchildren);
+            }
+         
+            Root.Items.Remove(child);
+            FirstContain.Children.Add(child);
+
+            base.AddChild(child);
+        }
+
+        public override void RemoveChild(BlockDesignerItemViewModel child)
+        {         
+            Root.Items.Add(child);
+            FirstContain.Children.Remove(child);
+
+            this.RemoveFromSelection();
+            child.AddToSelection(true, false);
+
+            base.RemoveChild(child);
+        }
+    }
+}