Have regression testing return to the listbox window when a test has completed.

EduNetworkBuilder/NetworkBuilder.cs

@@ -2965,7 +2965,11 @@ namespace EduNetworkBuilder
         private void regressionTestingToolStripMenuItem_Click(object sender, EventArgs e)
         {
             ListBoxWindow LBW = new ListBoxWindow(null, LBContents.regressiontest);
-            LBW.ShowDialog();
+            //We want to show dialog, but it needs to go to the background.  After that,
+            //It returns from the show dialog.  So we need to loop continuously until
+            //It is completed.
+            while (!LBW.ClosingRegression)
+                LBW.ShowDialog();
         }
 
         #endregion