Fixed creating/opening/closing twainsession multiple times in an app not working.

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();
+        }
+    }
+}