diff --git a/AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/DesignerItemViewModelBase.cs b/AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/DesignerItemViewModelBase.cs
index 55fd508..f7142ff 100644
--- a/AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/DesignerItemViewModelBase.cs
+++ b/AIStudio.Wpf.DiagramDesigner/ViewModels/BaseViewModel/DesignerItemViewModelBase.cs
@@ -358,7 +358,7 @@ namespace AIStudio.Wpf.DiagramDesigner
             }
         }
 
-        private double _left;
+        protected double _left;
         [CanDo]
         [Browsable(true)]
         public double Left