Tweak internal message pump form to be hidden.

src/Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <!--change these in each release-->
     <VersionPrefix>4.0.0.0</VersionPrefix>
-    <VersionSuffix>alpha.21</VersionSuffix>
+    <VersionSuffix>alpha.22</VersionSuffix>
     
     <!--keep it the same until major # changes-->
     <AssemblyVersion>4.0.0.0</AssemblyVersion>

src/NTwain/MessagePumpThread.cs

@@ -117,6 +117,17 @@ namespace NTwain
             {
                 ShowInTaskbar = false;
                 WindowState = FormWindowState.Minimized;
+                Text = "NTwain Internal Loop";
+            }
+
+            protected override CreateParams CreateParams
+            {
+                get
+                {
+                    CreateParams cp = base.CreateParams;
+                    cp.ExStyle |= 0x80; // WS_EX_TOOLWINDOW
+                    return cp;
+                }
             }
 
             protected override void OnShown(EventArgs e)