diff --git a/NTwain/Internals/InternalMessageLoopHook.cs b/NTwain/Internals/InternalMessageLoopHook.cs
index 28379c8..6b622b9 100644
--- a/NTwain/Internals/InternalMessageLoopHook.cs
+++ b/NTwain/Internals/InternalMessageLoopHook.cs
@@ -9,7 +9,7 @@ using System.Windows.Threading;
 
 namespace NTwain.Internals
 {
-    sealed class InternalMessageLoopHook : MessageLoopHook
+   sealed class InternalMessageLoopHook : MessageLoopHook
     {
         Dispatcher _dispatcher;
         WindowsHook _hook;
@@ -55,14 +55,14 @@ namespace NTwain.Internals
             }
         }
 
-        internal override void BeginInvoke(Action action)
+        public override void BeginInvoke(Action action)
         {
             if (_dispatcher == null) { throw new InvalidOperationException(Resources.MsgLoopUnavailble); }
 
             _dispatcher.BeginInvoke(DispatcherPriority.Normal, action);
         }
 
-        internal override void Invoke(Action action)
+        public override void Invoke(Action action)
         {
             if (_dispatcher == null) { throw new InvalidOperationException(Resources.MsgLoopUnavailble); }
 
diff --git a/NTwain/MessageLoopHooks.cs b/NTwain/MessageLoopHooks.cs
index 30d236d..fd3fcd5 100644
--- a/NTwain/MessageLoopHooks.cs
+++ b/NTwain/MessageLoopHooks.cs
@@ -16,7 +16,11 @@ namespace NTwain
         internal abstract void Start(IWinMessageFilter filter);
         internal abstract void Stop();
 
-        internal virtual void BeginInvoke(Action action)
+        /// <summary>
+        /// Asynchronously invokes the specified action on the message loop thread.
+        /// </summary>
+        /// <param name="action">The action.</param>
+        public virtual void BeginInvoke(Action action)
         {
             if (SyncContext == null)
             {
@@ -30,7 +34,12 @@ namespace NTwain
                 }, null);
             }
         }
-        internal virtual void Invoke(Action action)
+
+        /// <summary>
+        /// Synchronously invokes the specified action on the message loop thread.
+        /// </summary>
+        /// <param name="action">The action.</param>
+        public virtual void Invoke(Action action)
         {
             if (SyncContext == null)
             {
diff --git a/NTwain/Properties/VersionInfo.cs b/NTwain/Properties/VersionInfo.cs
index 7be4146..be3ac3c 100644
--- a/NTwain/Properties/VersionInfo.cs
+++ b/NTwain/Properties/VersionInfo.cs
@@ -14,6 +14,6 @@ namespace NTwain
         // keep this same in majors releases
         public const string Release = "2.0.0.0";
         // change this for each nuget release
-        public const string Build = "2.0.4";
+        public const string Build = "2.0.5";
     }
 }
\ No newline at end of file
diff --git a/NTwain/TwainSession.cs b/NTwain/TwainSession.cs
index d34ebd8..60736a6 100644
--- a/NTwain/TwainSession.cs
+++ b/NTwain/TwainSession.cs
@@ -54,12 +54,18 @@ namespace NTwain
 
         internal static TwainSource GetSourceInstance(ITwainSessionInternal session, TWIdentity sourceId)
         {
+            TwainSource source = null;
             var key = string.Format(CultureInfo.InvariantCulture, "{0}|{1}|{2}", sourceId.Manufacturer, sourceId.ProductFamily, sourceId.ProductName);
             if (__ownedSources.ContainsKey(key))
             {
-                return __ownedSources[key];
+                source = __ownedSources[key];
+                source.Session = session;
             }
-            return __ownedSources[key] = new TwainSource(session, sourceId);
+            else
+            {
+                __ownedSources[key] = source = new TwainSource(session, sourceId);
+            }
+            return source;
         }
 
         /// <summary>
diff --git a/NTwain/TwainSource.Caps.cs b/NTwain/TwainSource.Caps.cs
index 7b01ad1..3948aae 100644
--- a/NTwain/TwainSource.Caps.cs
+++ b/NTwain/TwainSource.Caps.cs
@@ -18,7 +18,7 @@ namespace NTwain
             QuerySupport retVal = QuerySupport.None;
             using (TWCapability cap = new TWCapability(capId))
             {
-                var rc = _session.DGControl.Capability.QuerySupport(cap);
+                var rc = Session.DGControl.Capability.QuerySupport(cap);
                 if (rc == ReturnCode.Success)
                 {
                     var read = CapabilityReader.ReadValue(cap);
@@ -41,7 +41,7 @@ namespace NTwain
         {
             using (TWCapability cap = new TWCapability(capId))
             {
-                var rc = _session.DGControl.Capability.GetCurrent(cap);
+                var rc = Session.DGControl.Capability.GetCurrent(cap);
                 if (rc == ReturnCode.Success)
                 {
                     var read = CapabilityReader.ReadValue(cap);
@@ -82,7 +82,7 @@ namespace NTwain
             var list = new List<object>();
             using (TWCapability cap = new TWCapability(capabilityId))
             {
-                var rc = _session.DGControl.Capability.Get(cap);
+                var rc = Session.DGControl.Capability.Get(cap);
                 if (rc == ReturnCode.Success)
                 {
                     cap.ReadMultiCapValues(list);
@@ -126,7 +126,7 @@ namespace NTwain
         {
             using (TWCapability compressCap = new TWCapability(CapabilityId.ICapCompression, new TWOneValue { Item = (uint)compression, ItemType = ItemType.UInt16 }))
             {
-                return _session.DGControl.Capability.Set(compressCap);
+                return Session.DGControl.Capability.Set(compressCap);
             }
         }
 
@@ -153,7 +153,7 @@ namespace NTwain
         {
             using (TWCapability formatCap = new TWCapability(CapabilityId.ICapImageFileFormat, new TWOneValue { Item = (uint)format, ItemType = ItemType.UInt16 }))
             {
-                return _session.DGControl.Capability.Set(formatCap);
+                return Session.DGControl.Capability.Set(formatCap);
             }
         }
 
@@ -183,7 +183,7 @@ namespace NTwain
             one.ItemType = ItemType.UInt16;
             using (TWCapability dx = new TWCapability(CapabilityId.ICapPixelType, one))
             {
-                return _session.DGControl.Capability.Set(dx);
+                return Session.DGControl.Capability.Set(dx);
             }
         }
 
@@ -223,7 +223,7 @@ namespace NTwain
             one.ItemType = ItemType.UInt16;
             using (TWCapability dx = new TWCapability(CapabilityId.ICapXferMech, one))
             {
-                return _session.DGControl.Capability.Set(dx);
+                return Session.DGControl.Capability.Set(dx);
             }
         }
 
@@ -239,7 +239,7 @@ namespace NTwain
             one.ItemType = ItemType.UInt16;
             using (TWCapability dx = new TWCapability(CapabilityId.ACapXferMech, one))
             {
-                return _session.DGControl.Capability.Set(dx);
+                return Session.DGControl.Capability.Set(dx);
             }
         }
 
@@ -282,13 +282,13 @@ namespace NTwain
 
             using (TWCapability xres = new TWCapability(CapabilityId.ICapXResolution, one))
             {
-                var rc = _session.DGControl.Capability.Set(xres);
+                var rc = Session.DGControl.Capability.Set(xres);
                 if (rc == ReturnCode.Success)
                 {
                     one.Item = (uint)yDPI;
                     using (TWCapability yres = new TWCapability(CapabilityId.ICapYResolution, one))
                     {
-                        rc = _session.DGControl.Capability.Set(yres);
+                        rc = Session.DGControl.Capability.Set(yres);
                     }
                 }
                 return rc;
@@ -322,7 +322,7 @@ namespace NTwain
 
             using (TWCapability xres = new TWCapability(CapabilityId.ICapSupportedSizes, one))
             {
-                var rc = _session.DGControl.Capability.Set(xres);
+                var rc = Session.DGControl.Capability.Set(xres);
                 return rc;
             }
         }
@@ -351,7 +351,7 @@ namespace NTwain
 
                     using (TWCapability dx = new TWCapability(CapabilityId.ICapAutomaticDeskew, en))
                     {
-                        rc = _session.DGControl.Capability.Set(dx);
+                        rc = Session.DGControl.Capability.Set(dx);
                     }
                 }
                 else
@@ -362,7 +362,7 @@ namespace NTwain
 
                     using (TWCapability capValue = new TWCapability(CapabilityId.ICapAutomaticDeskew, one))
                     {
-                        rc = _session.DGControl.Capability.Set(capValue);
+                        rc = Session.DGControl.Capability.Set(capValue);
                     }
                 }
             }
@@ -389,7 +389,7 @@ namespace NTwain
 
                     using (TWCapability dx = new TWCapability(CapabilityId.ICapAutomaticRotate, en))
                     {
-                        rc = _session.DGControl.Capability.Set(dx);
+                        rc = Session.DGControl.Capability.Set(dx);
                     }
                 }
                 else
@@ -400,7 +400,7 @@ namespace NTwain
 
                     using (TWCapability capValue = new TWCapability(CapabilityId.ICapAutomaticRotate, one))
                     {
-                        rc = _session.DGControl.Capability.Set(capValue);
+                        rc = Session.DGControl.Capability.Set(capValue);
                     }
                 }
             }
@@ -428,11 +428,11 @@ namespace NTwain
 
                     using (TWCapability dx = new TWCapability(CapabilityId.ICapUndefinedImageSize, en))
                     {
-                        rc = _session.DGControl.Capability.Set(dx);
+                        rc = Session.DGControl.Capability.Set(dx);
                     }
                     using (TWCapability dx = new TWCapability(CapabilityId.ICapAutomaticBorderDetection, en))
                     {
-                        rc = _session.DGControl.Capability.Set(dx);
+                        rc = Session.DGControl.Capability.Set(dx);
                     }
                 }
                 else
@@ -443,11 +443,11 @@ namespace NTwain
 
                     using (TWCapability capValue = new TWCapability(CapabilityId.ICapUndefinedImageSize, one))
                     {
-                        rc = _session.DGControl.Capability.Set(capValue);
+                        rc = Session.DGControl.Capability.Set(capValue);
                     }
                     using (TWCapability capValue = new TWCapability(CapabilityId.ICapAutomaticBorderDetection, one))
                     {
-                        rc = _session.DGControl.Capability.Set(capValue);
+                        rc = Session.DGControl.Capability.Set(capValue);
                     }
                 }
             }
@@ -471,7 +471,7 @@ namespace NTwain
 
                 using (TWCapability dx = new TWCapability(CapabilityId.CapDuplexEnabled, en))
                 {
-                    return _session.DGControl.Capability.Set(dx);
+                    return Session.DGControl.Capability.Set(dx);
                 }
             }
             else
@@ -482,7 +482,7 @@ namespace NTwain
 
                 using (TWCapability dx = new TWCapability(CapabilityId.CapDuplexEnabled, one))
                 {
-                    return _session.DGControl.Capability.Set(dx);
+                    return Session.DGControl.Capability.Set(dx);
                 }
             }
         }
@@ -512,7 +512,7 @@ namespace NTwain
                     {
                         using (TWCapability dx = new TWCapability(CapabilityId.CapFeederEnabled, en))
                         {
-                            rc = _session.DGControl.Capability.Set(dx);
+                            rc = Session.DGControl.Capability.Set(dx);
                         }
                     }
 
@@ -522,14 +522,14 @@ namespace NTwain
                     {
                         using (TWCapability dx = new TWCapability(CapabilityId.CapAutoScan, en))
                         {
-                            rc = _session.DGControl.Capability.Set(dx);
+                            rc = Session.DGControl.Capability.Set(dx);
                         }
                     }
                     else if (SupportedCaps.Contains(CapabilityId.CapAutoFeed))
                     {
                         using (TWCapability dx = new TWCapability(CapabilityId.CapAutoFeed, en))
                         {
-                            rc = _session.DGControl.Capability.Set(dx);
+                            rc = Session.DGControl.Capability.Set(dx);
                         }
                     }
                 }
@@ -543,7 +543,7 @@ namespace NTwain
                     {
                         using (TWCapability enabled = new TWCapability(CapabilityId.CapFeederEnabled, one))
                         {
-                            rc = _session.DGControl.Capability.Set(enabled);
+                            rc = Session.DGControl.Capability.Set(enabled);
                         }
                     }
                     // to really use feeder we must also set autofeed or autoscan, but only
@@ -552,14 +552,14 @@ namespace NTwain
                     {
                         using (TWCapability autoScan = new TWCapability(CapabilityId.CapAutoScan, one))
                         {
-                            rc = _session.DGControl.Capability.Set(autoScan);
+                            rc = Session.DGControl.Capability.Set(autoScan);
                         }
                     }
                     else if (SupportedCaps.Contains(CapabilityId.CapAutoFeed))
                     {
                         using (TWCapability autoScan = new TWCapability(CapabilityId.CapAutoFeed, one))
                         {
-                            rc = _session.DGControl.Capability.Set(autoScan);
+                            rc = Session.DGControl.Capability.Set(autoScan);
                         }
                     }
                 }
diff --git a/NTwain/TwainSource.cs b/NTwain/TwainSource.cs
index b9b2736..eb064f6 100644
--- a/NTwain/TwainSource.cs
+++ b/NTwain/TwainSource.cs
@@ -17,11 +17,11 @@ namespace NTwain
     /// </summary>
     public partial class TwainSource
     {
-        ITwainSessionInternal _session;
+        internal ITwainSessionInternal Session { get; set; }
 
         internal TwainSource(ITwainSessionInternal session, TWIdentity sourceId)
         {
-            _session = session;
+            Session = session;
             Identity = sourceId;
         }
 
@@ -32,11 +32,11 @@ namespace NTwain
         public ReturnCode Open()
         {
             var rc = ReturnCode.Failure;
-            _session.MessageLoopHook.Invoke(() =>
+            Session.MessageLoopHook.Invoke(() =>
             {
                 Debug.WriteLine(string.Format(CultureInfo.InvariantCulture, "Thread {0}: OpenSource.", Thread.CurrentThread.ManagedThreadId));
 
-                rc = _session.DGControl.Identity.OpenDS(this);
+                rc = Session.DGControl.Identity.OpenDS(this);
             });
             return rc;
         }
@@ -48,11 +48,11 @@ namespace NTwain
         public ReturnCode Close()
         {
             var rc = ReturnCode.Failure;
-            _session.MessageLoopHook.Invoke(() =>
+            Session.MessageLoopHook.Invoke(() =>
             {
                 Debug.WriteLine(string.Format(CultureInfo.InvariantCulture, "Thread {0}: CloseSource.", Thread.CurrentThread.ManagedThreadId));
 
-                rc = _session.DGControl.Identity.CloseDS();
+                rc = Session.DGControl.Identity.CloseDS();
                 if (rc == ReturnCode.Success)
                 {
                     SupportedCaps = null;
@@ -71,7 +71,7 @@ namespace NTwain
         /// <returns></returns>
         public ReturnCode StartTransfer(SourceEnableMode mode, bool modal, IntPtr windowHandle)
         {
-            return _session.EnableSource(mode, modal, windowHandle);
+            return Session.EnableSource(mode, modal, windowHandle);
         }
 
         /// <summary>
@@ -81,7 +81,7 @@ namespace NTwain
         public TWStatus GetStatus()
         {
             TWStatus stat;
-            _session.DGControl.Status.GetSource(out stat);
+            Session.DGControl.Status.GetSource(out stat);
             return stat;
         }
         /// <summary>
@@ -91,7 +91,7 @@ namespace NTwain
         public TWStatusUtf8 GetStatusUtf8()
         {
             TWStatusUtf8 stat;
-            _session.DGControl.StatusUtf8.GetSource(out stat);
+            Session.DGControl.StatusUtf8.GetSource(out stat);
             return stat;
         }
 
@@ -170,7 +170,7 @@ namespace NTwain
         {
             get
             {
-                if (_supportedCaps == null && _session.State > 3)
+                if (_supportedCaps == null && Session.State > 3)
                 {
                     _supportedCaps = CapGetValues(CapabilityId.CapSupportedCaps).CastToEnum<CapabilityId>(false);
                 }
@@ -191,7 +191,7 @@ namespace NTwain
         {
             get
             {
-                return _session.DGControl;
+                return Session.DGControl;
             }
         }
 
@@ -202,7 +202,7 @@ namespace NTwain
         {
             get
             {
-                return _session.DGImage;
+                return Session.DGImage;
             }
         }
 
@@ -213,7 +213,7 @@ namespace NTwain
         {
             get
             {
-                return _session.DGCustom;
+                return Session.DGCustom;
             }
         }
 
@@ -232,7 +232,7 @@ namespace NTwain
         ///// <param name="propertyName">Name of the property.</param>
         //protected void OnPropertyChanged(string propertyName)
         //{
-        //    var syncer = _session.SynchronizationContext;
+        //    var syncer = Session.SynchronizationContext;
         //    if (syncer == null)
         //    {
         //        try
diff --git a/Tests/Tester.WPF/App.xaml b/Tests/Tester.WPF/App.xaml
index d733b8c..9ea9427 100644
--- a/Tests/Tester.WPF/App.xaml
+++ b/Tests/Tester.WPF/App.xaml
@@ -1,7 +1,7 @@
 <Application x:Class="Tester.WPF.App"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             StartupUri="MainWindow.xaml">
+             StartupUri="Dummy.xaml">
 	<Application.Resources>
         <ResourceDictionary>
             <!-- Dummy Style, anything you won't use goes -->
diff --git a/Tests/Tester.WPF/Dummy.xaml b/Tests/Tester.WPF/Dummy.xaml
new file mode 100644
index 0000000..9304408
--- /dev/null
+++ b/Tests/Tester.WPF/Dummy.xaml
@@ -0,0 +1,12 @@
+<Window x:Class="Tester.WPF.Dummy"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Dummy" Height="300" Width="300">
+    <Grid>
+        <StackPanel VerticalAlignment="Center">
+            <Button Content="Open scan window" Click="Button_Click" Margin="4 0"></Button>
+            <TextBlock Text="This is to test opening/closing multiple twain sessions in an app" Margin="8"
+                       TextWrapping="Wrap"></TextBlock>
+        </StackPanel>
+    </Grid>
+</Window>
diff --git a/Tests/Tester.WPF/Dummy.xaml.cs b/Tests/Tester.WPF/Dummy.xaml.cs
new file mode 100644
index 0000000..8c055a9
--- /dev/null
+++ b/Tests/Tester.WPF/Dummy.xaml.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
+
+namespace Tester.WPF
+{
+    /// <summary>
+    /// Interaction logic for Dummy.xaml
+    /// </summary>
+    public partial class Dummy : Window
+    {
+        public Dummy()
+        {
+            InitializeComponent();
+        }
+
+        private void Button_Click(object sender, RoutedEventArgs e)
+        {
+            new MainWindow().ShowDialog();
+        }
+    }
+}
diff --git a/Tests/Tester.WPF/MainWindow.xaml.cs b/Tests/Tester.WPF/MainWindow.xaml.cs
index 72a3198..c5b167b 100644
--- a/Tests/Tester.WPF/MainWindow.xaml.cs
+++ b/Tests/Tester.WPF/MainWindow.xaml.cs
@@ -4,6 +4,7 @@ using NTwain;
 using NTwain.Data;
 using System;
 using System.ComponentModel;
+using System.Diagnostics;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -51,13 +52,18 @@ namespace Tester.WPF
                 });
             }
         }
-
+        protected override void OnClosing(CancelEventArgs e)
+        {
+            e.Cancel = _twainVM.State > 4;
+            base.OnClosing(e);
+        }
         protected override void OnClosed(EventArgs e)
         {
             if (_twainVM.State == 4)
             {
                 _twainVM.CurrentSource.Close();
             }
+            _twainVM.Close();
             base.OnClosed(e);
         }
 
@@ -68,6 +74,8 @@ namespace Tester.WPF
             // use this for internal msg loop
             //var rc = _twainVM.Open();
             // use this to hook into current app loop
+
+
             var rc = _twainVM.Open(new WpfMessageLoopHook(new WindowInteropHelper(this).Handle));
 
             if (rc == ReturnCode.Success)
@@ -82,6 +90,15 @@ namespace Tester.WPF
 
         private void SrcList_SelectionChanged(object sender, SelectionChangedEventArgs e)
         {
+
+            //var test = new NTwain.Internals.InternalMessageLoopHook();
+            //test.StartTest();
+            //test.BeginInvoke(() =>
+            //{
+            //    Debug.WriteLine("doodle");
+            //    test.StopTest();
+            //});
+
             if (_twainVM.State == 4)
             {
                 _twainVM.CurrentSource.Close();
diff --git a/Tests/Tester.WPF/Tester.WPF.csproj b/Tests/Tester.WPF/Tester.WPF.csproj
index b7b2cd3..54e4e0b 100644
--- a/Tests/Tester.WPF/Tester.WPF.csproj
+++ b/Tests/Tester.WPF/Tester.WPF.csproj
@@ -80,7 +80,14 @@
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
     </ApplicationDefinition>
+    <Compile Include="Dummy.xaml.cs">
+      <DependentUpon>Dummy.xaml</DependentUpon>
+    </Compile>
     <Compile Include="ViewModels\TwainVM.cs" />
+    <Page Include="Dummy.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="MainWindow.xaml">
       <Generator>MSBuild:Compile</Generator>
       <SubType>Designer</SubType>
diff --git a/Tests/Tester.WPF/ViewModels/TwainVM.cs b/Tests/Tester.WPF/ViewModels/TwainVM.cs
index 8153351..51ece2a 100644
--- a/Tests/Tester.WPF/ViewModels/TwainVM.cs
+++ b/Tests/Tester.WPF/ViewModels/TwainVM.cs
@@ -3,6 +3,7 @@ using GalaSoft.MvvmLight.Messaging;
 using NTwain;
 using NTwain.Data;
 using System;
+using System.IO;
 using System.Reflection;
 using System.Threading;
 using System.Windows.Media;
@@ -76,12 +77,23 @@ namespace Tester.WPF
                 var fileSetup = new TWSetupFileXfer
                 {
                     Format = wantFormat,
-                    FileName = System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "test.tif")
+                    FileName = GetUniqueName(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "test", ".tif")
                 };
                 var rc = this.CurrentSource.DGControl.SetupFileXfer.Set(fileSetup);
             }
         }
 
+        private string GetUniqueName(string dir, string name, string ext)
+        {
+            var filePath = Path.Combine(dir, name + ext);
+            int next = 1;
+            while (File.Exists(filePath))
+            {
+                filePath = Path.Combine(dir, string.Format("{0} ({1}){2}", name, next++, ext));
+            }
+            return filePath;
+        }
+
         protected override void OnDataTransferred(DataTransferredEventArgs e)
         {
             ImageSource img = null;
diff --git a/Tests/Tester.Winform/TestForm.cs b/Tests/Tester.Winform/TestForm.cs
index 427cb8b..dad7dbb 100644
--- a/Tests/Tester.Winform/TestForm.cs
+++ b/Tests/Tester.Winform/TestForm.cs
@@ -245,7 +245,7 @@ namespace Tester.Winform
                 // use this for internal msg loop
                 _twain.Open();
                 // use this to hook into current app loop
-                //_twain.Open(new WinformMessageLoopHook(this.Handle));
+                //_twain.Open(new WindowsFormsMessageLoopHook(this.Handle));
             }
 
             if (_twain.State >= 3)