add AboutWindow

HandyControlDemo/UserControl/Main/NoUserContent.xaml

@@ -56,6 +56,7 @@
                         <Path Data="{StaticResource CnblogsGeometry}" Fill="{DynamicResource PrimaryTextBrush}"/>
                     </MenuItem.Icon>
                 </MenuItem>
+                <MenuItem Header="{x:Static langs:Lang.About}" Click="MenuAbout_OnClick"/>
             </MenuItem>
             <MenuItem Click="MenuItemContributors_OnClick" Foreground="White" Header="{x:Static langs:Lang.Contributors}">
                 <MenuItem.Icon>

HandyControlDemo/UserControl/Main/NoUserContent.xaml.cs

@@ -8,6 +8,7 @@ using HandyControl.Controls;
 using HandyControl.Data;
 using HandyControlDemo.Data;
 using HandyControlDemo.Tools;
+using HandyControlDemo.Window;
 
 // ReSharper disable once CheckNamespace
 namespace HandyControlDemo.UserControl
@@ -72,5 +73,13 @@ namespace HandyControlDemo.UserControl
             Messenger.Default.Send(true, MessageToken.FullSwitch);
             Messenger.Default.Send(AssemblyHelper.CreateInternalInstance($"UserControl.{MessageToken.ContributorsView}"), MessageToken.LoadShowContent);
         }
+
+        private void MenuAbout_OnClick(object sender, RoutedEventArgs e)
+        {
+            new AboutWindow
+            {
+                Owner = Application.Current.MainWindow
+            }.ShowDialog();
+        }
     }
 }