refactored MainActivity to utilize itemId in listview instead of querying with portfolio name for context menu...still not happy with this, but I did learn about .NET's lack of Anonymous Inner Classes, so that's something

MonoStockPortfolio.Entities/Portfolio.cs

@@ -1,7 +1,3 @@
-using System;
-using System.Collections.Generic;
-using System.Runtime.Serialization;
-
 namespace MonoStockPortfolio.Entities
 {
     public class Portfolio
@@ -11,11 +7,5 @@ namespace MonoStockPortfolio.Entities
 
         public long? ID { get; private set; }
         public string Name { get; set; }
-
-        public void GetObjectData(SerializationInfo info, StreamingContext context)
-        {
-            info.AddValue("ID", this.ID);
-            info.AddValue("Name", this.Name);
-        }
     }
 }

MonoStockPortfolio/Activites/MainScreen/IMainPresenter.cs

@@ -10,6 +10,5 @@
         void EditPortfolio(int itemId);
         void GotoConfig();
         void ExitApplication();
-        int GetPortfolioIdForContextMenu(string selectedPortfolioName);
     }
 }

MonoStockPortfolio/Activites/MainScreen/IMainView.cs

@@ -1,10 +1,11 @@
 using System.Collections.Generic;
+using MonoStockPortfolio.Entities;
 
 namespace MonoStockPortfolio.Activites.MainScreen
 {
     public interface IMainView
     {
-        void RefreshList(IList<string> portfolioNames);
+        void RefreshList(IList<Portfolio> portfolios);
         void StartAddPortfolioActivity();
         void StartViewPortfolioActivity(long portfolioId);
         void StartEditPortfolioActivity(int itemId);

MonoStockPortfolio/Activites/MainScreen/MainActivity.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Android.App;
 using Android.Content;
 using Android.OS;
@@ -8,6 +9,7 @@ using Android.Widget;
 using MonoStockPortfolio.Activites.ConfigScreen;
 using MonoStockPortfolio.Activites.EditPortfolioScreen;
 using MonoStockPortfolio.Activites.PortfolioScreen;
+using MonoStockPortfolio.Entities;
 using MonoStockPortfolio.Framework;
 
 namespace MonoStockPortfolio.Activites.MainScreen
@@ -33,9 +35,10 @@ namespace MonoStockPortfolio.Activites.MainScreen
 
         #region IMainView implementation
 
-        public void RefreshList(IList<string> portfolioNames)
+        public void RefreshList(IList<Portfolio> portfolios)
         {
-            var listAdapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleListItem1, portfolioNames);
+            var portfolioLabels = portfolios.Select(p => p.Name).ToArray();
+            var listAdapter = new PortfolioArrayAdapter(this, Android.Resource.Layout.SimpleListItem1, portfolios, portfolioLabels);
             PortfolioListView.Adapter = listAdapter;
         }
 
@@ -82,9 +85,7 @@ namespace MonoStockPortfolio.Activites.MainScreen
             base.OnCreateContextMenu(menu, v, menuInfo);
 
             var info = (AdapterView.AdapterContextMenuInfo)menuInfo;
-            var selectedPortfolioName = ((TextView)info.TargetView).Text.ToS();
-
-            var id = _presenter.GetPortfolioIdForContextMenu(selectedPortfolioName);
+            var id = (int)info.Id;
 
             menu.SetHeaderTitle("Options".ToJ());
             menu.Add(0, id, 1, "Rename".ToJ());

MonoStockPortfolio/Activites/MainScreen/MainPresenter.cs

@@ -1,7 +1,5 @@
 using System.Collections.Generic;
-using Android.Runtime;
 using MonoStockPortfolio.Core.PortfolioRepositories;
-using System.Linq;
 using MonoStockPortfolio.Entities;
 
 namespace MonoStockPortfolio.Activites.MainScreen
@@ -35,8 +33,7 @@ namespace MonoStockPortfolio.Activites.MainScreen
         public void RefreshPortfolioList()
         {
             _portfolios = null;
-            var portfolioNames = Portfolios.Select(p => p.Name).ToList();
-            _currentView.RefreshList(portfolioNames);
+            _currentView.RefreshList(Portfolios);
         }
 
         public void AddNewPortfolio()
@@ -68,12 +65,5 @@ namespace MonoStockPortfolio.Activites.MainScreen
         {
             _currentView.ExitApplication();
         }
-
-        public int GetPortfolioIdForContextMenu(string selectedPortfolioName)
-        {
-            var selectedPortfolio = _repo.GetPortfolioByName(selectedPortfolioName);
-            var id = (int)(selectedPortfolio.ID ?? -1);
-            return id;
-        }
     }
 }

MonoStockPortfolio/Activites/MainScreen/PortfolioArrayAdapter.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+using Android.Content;
+using Android.Widget;
+using MonoStockPortfolio.Entities;
+
+namespace MonoStockPortfolio.Activites.MainScreen
+{
+    public class PortfolioArrayAdapter : ArrayAdapter<string>
+    {
+        private readonly IList<Portfolio> _results;
+
+        public PortfolioArrayAdapter(Context context, int resource, IList<Portfolio> results, IList<string> labels) 
+            : base(context, resource, labels)
+        {
+            _results = results;
+        }
+
+        public override long GetItemId(int position)
+        {
+            return _results[position].ID ?? -1;
+        }
+    }
+}

MonoStockPortfolio/Activites/PortfolioScreen/PositionArrayAdapter.cs

@@ -10,7 +10,7 @@ namespace MonoStockPortfolio.Activites.PortfolioScreen
 {
     public class PositionArrayAdapter : GenericArrayAdapter<PositionResultsViewModel>
     {
-        private IEnumerable<StockDataItem> _configItems;
+        private readonly IEnumerable<StockDataItem> _configItems;
 
         public PositionArrayAdapter(Context context, IEnumerable<PositionResultsViewModel> results, IEnumerable<StockDataItem> configItems)
             : base(context, results)

MonoStockPortfolio/Framework/StringExtensions.cs

@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using Java.Lang;
-using StringBuilder = System.Text.StringBuilder;
 
 namespace MonoStockPortfolio.Framework
 {

MonoStockPortfolio/MonoStockPortfolio.csproj

@@ -66,6 +66,7 @@
     <Compile Include="Activites\EditPositionScreen\IEditPositionPresenter.cs" />
     <Compile Include="Activites\EditPositionScreen\IEditPositionView.cs" />
     <Compile Include="Activites\EditPositionScreen\PositionInputModel.cs" />
+    <Compile Include="Activites\MainScreen\PortfolioArrayAdapter.cs" />
     <Compile Include="Framework\FormValidator.cs" />
     <Compile Include="Activites\MainScreen\IMainPresenter.cs" />
     <Compile Include="Activites\MainScreen\IMainView.cs" />