部分连接线完成，另外待连接点红色区域显示。

AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/Connector/ConnectorInfoBase.cs

@@ -145,6 +145,19 @@ namespace AIStudio.Wpf.DiagramDesigner
             }
         }
 
+        private bool _beAttachTo;
+        public bool BeAttachTo
+        {
+            get
+            {
+                return _beAttachTo;
+            }
+            set
+            {
+                SetProperty(ref _beAttachTo, value);
+            }
+        }
+
         public virtual bool CanAttachTo(ConnectorInfoBase port)
             => port != this && !port.IsReadOnly;
         #endregion