Merge pull request #40 from ghost1372/patch-10

Fix MessageBox for null Caption

HandyControl/Controls/Window/MessageBox.cs

@@ -1,6 +1,5 @@
 using System;
 using System.ComponentModel;
-using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
@@ -298,7 +297,7 @@ namespace HandyControl.Controls
                 Owner = ownerWindow,
                 WindowStartupLocation = ownerIsNull ? WindowStartupLocation.CenterScreen : WindowStartupLocation.CenterOwner,
                 ShowTitle = true,
-                Title = caption,
+                Title = caption ?? string.Empty,
                 Topmost = ownerIsNull,
                 _messageBoxResult = defaultResult
             };
@@ -388,4 +387,4 @@ namespace HandyControl.Controls
                    || value == MessageBoxResult.Yes;
         }
     }
-}
+}