Fix structure reorder position

app/controllers/admin/items_controller.rb

@@ -27,7 +27,7 @@ class Admin::ItemsController < OrbitBackendController
 
   def update_position
     item = Item.find(params[:id])
-    item.shift_to(params[:parent_id], params[:position])
+    item.shift_to(params[:parent_id], params[:position].to_i - 1)
     render :nothing => true
   end