diff --git a/AIStudio.Wpf.DiagramDesigner/Controls/ResizeThumb.cs b/AIStudio.Wpf.DiagramDesigner/Controls/ResizeThumb.cs
index c6cd60f..86d0158 100644
--- a/AIStudio.Wpf.DiagramDesigner/Controls/ResizeThumb.cs
+++ b/AIStudio.Wpf.DiagramDesigner/Controls/ResizeThumb.cs
@@ -133,7 +133,7 @@ namespace AIStudio.Wpf.DiagramDesigner.Controls
 
         #region Helper methods
 
-        private void DragLeft(double scale, DesignerItemViewModelBase item, DiagramSelectionService selectionService)
+        private void DragLeft(double scale, DesignerItemViewModelBase item, SelectionService selectionService)
         {
             IEnumerable<DesignerItemViewModelBase> groupItems = selectionService.GetGroupMembers(item, false).Cast<DesignerItemViewModelBase>();
 
@@ -147,7 +147,7 @@ namespace AIStudio.Wpf.DiagramDesigner.Controls
             }
         }
 
-        private void DragTop(double scale, DesignerItemViewModelBase item, DiagramSelectionService selectionService)
+        private void DragTop(double scale, DesignerItemViewModelBase item, SelectionService selectionService)
         {
             IEnumerable<DesignerItemViewModelBase> groupItems = selectionService.GetGroupMembers(item, false).Cast<DesignerItemViewModelBase>();
             double groupBottom = item.Top + item.GetItemHeight();
@@ -160,7 +160,7 @@ namespace AIStudio.Wpf.DiagramDesigner.Controls
             }
         }
 
-        private void DragRight(double scale, DesignerItemViewModelBase item, DiagramSelectionService selectionService)
+        private void DragRight(double scale, DesignerItemViewModelBase item, SelectionService selectionService)
         {
             IEnumerable<DesignerItemViewModelBase> groupItems = selectionService.GetGroupMembers(item, false).Cast<DesignerItemViewModelBase>();
 
@@ -175,7 +175,7 @@ namespace AIStudio.Wpf.DiagramDesigner.Controls
             }
         }
 
-        private void DragBottom(double scale, DesignerItemViewModelBase item, DiagramSelectionService selectionService)
+        private void DragBottom(double scale, DesignerItemViewModelBase item, SelectionService selectionService)
         {
             IEnumerable<DesignerItemViewModelBase> groupItems = selectionService.GetGroupMembers(item, false).Cast<DesignerItemViewModelBase>();
             double groupTop = item.Top;