Some more xml doc updates.

samples/NetCoreConsole/Program.cs

@@ -13,6 +13,7 @@ namespace NetCoreConsole
                 var config = new TwainConfigBuilder()
                     .DefineApp(Assembly.GetExecutingAssembly())
                     .Build();
+
                 Console.WriteLine($"App = {(config.Is64Bit ? "64bit" : "32bit")}");
                 Console.WriteLine($"Platform = {config.Platform}");
                 Console.WriteLine();
@@ -38,8 +39,6 @@ namespace NetCoreConsole
                         var selectSrc = session.ShowSourceSelector();
                         Console.WriteLine($"Selected data source = {selectSrc}");
                         Console.WriteLine();
-
-                        //session.DefaultSource = null;
                     }
 
                 }

src/NTwain/Data/TwainTypesExtended.cs

@@ -2288,6 +2288,12 @@ namespace NTwain.Data
     /// </summary>
     public partial struct TW_TWAINDIRECT
     {
+        /// <summary>
+        /// Constructs this struct.
+        /// </summary>
+        /// <param name="manager"></param>
+        /// <param name="send"></param>
+        /// <param name="sendSize"></param>
         public TW_TWAINDIRECT(ushort manager, IntPtr send, uint sendSize)
         {
             _SizeOf = (uint)Marshal.SizeOf(typeof(TW_TWAINDIRECT));

src/NTwain/Data/TwainValues.cs

@@ -1,5 +1,7 @@
 using System;
 
+#pragma warning disable 1591
+
 namespace NTwain.Data
 {
     // these are from the corresponding twain.h sections
@@ -2081,3 +2083,5 @@ namespace NTwain.Data
         True = 1
     }
 }
+
+#pragma warning restore 1591

src/NTwain/TwainConfig.cs

@@ -9,12 +9,21 @@ using System.Text;
 
 namespace NTwain
 {
+    /// <summary>
+    /// Contains settings and platform info for a <see cref="TwainSession"/>.
+    /// </summary>
     public class TwainConfig
     {
         internal TwainConfig() { }
 
+        /// <summary>
+        /// Gets whether the app is running in 64bit.
+        /// </summary>
         public bool Is64Bit { get; internal set; }
 
+        /// <summary>
+        /// Gets the platform the app is running on.
+        /// </summary>
         public PlatformID Platform { get; internal set; }
 
         //public bool PreferLegacyDsm { get; internal set; }
@@ -23,7 +32,9 @@ namespace NTwain
 
         internal TW_IDENTITY SrcWin32 { get; set; }
 
-
+        /// <summary>
+        /// Gets memory manager associated with a <see cref="TwainSession"/>.
+        /// </summary>
         public IMemoryManager MemoryManager { get; internal set; }
     }
 }

src/NTwain/TwainSession.cs

@@ -75,7 +75,7 @@ namespace NTwain
         }
 
         /// <summary>
-        /// Gets/sets the default data source.
+        /// Gets/sets the default data source. Setting to null is not supported.
         /// </summary>
         public DataSource DefaultSource
         {
@@ -90,14 +90,17 @@ namespace NTwain
             }
             set
             {
-                //if (value != null && value.Session != this)
-                //{
-                //    throw new InvalidOperationException("Source is not from this session.");
-                //}
-                DGControl.Identity.Set(value);
+                if (value != null)
+                {
+                    if (value.Session != this)
+                    {
+                        throw new InvalidOperationException("Source is not from this session.");
+                    }
+                    var rc = DGControl.Identity.Set(value);
                     RaisePropertyChanged(nameof(DefaultSource));
                 }
             }
+        }
 
         /// <summary>
         /// Tries to show the built-in source selector dialog and return the selected source.