diff --git a/src/Shared/HandyControlDemo_Shared/MainWindow.xaml b/src/Shared/HandyControlDemo_Shared/MainWindow.xaml
index e82bc22b..9ff31060 100644
--- a/src/Shared/HandyControlDemo_Shared/MainWindow.xaml
+++ b/src/Shared/HandyControlDemo_Shared/MainWindow.xaml
@@ -12,9 +12,10 @@
                ShowTitle="False"
                ResizeMode="CanResizeWithGrip"
                WindowStartupLocation="CenterScreen"
-               hc:GlobalShortcut.Host="True"
                DataContext="{Binding Main,Source={StaticResource Locator}}"
+               hc:GlobalShortcut.Host="True"
                hc:Dialog.Token="{x:Static data:MessageToken.MainWindow}"
+               hc:WindowAttach.IgnoreAltF4="True"
                d:DesignHeight="800" 
                d:DesignWidth="1400" 
                Icon="/HandyControlDemo;component/Resources/Img/icon.ico">
diff --git a/src/Shared/HandyControl_Shared/Controls/Attach/WindowAttach.cs b/src/Shared/HandyControl_Shared/Controls/Attach/WindowAttach.cs
index 99909ec9..fb600659 100644
--- a/src/Shared/HandyControl_Shared/Controls/Attach/WindowAttach.cs
+++ b/src/Shared/HandyControl_Shared/Controls/Attach/WindowAttach.cs
@@ -37,5 +37,37 @@ namespace HandyControl.Controls
                 System.Windows.Window.GetWindow(obj)?.DragMove();
             }
         }
+
+        public static readonly DependencyProperty IgnoreAltF4Property = DependencyProperty.RegisterAttached(
+            "IgnoreAltF4", typeof(bool), typeof(WindowAttach), new PropertyMetadata(ValueBoxes.FalseBox, OnIgnoreAltF4Changed));
+
+        private static void OnIgnoreAltF4Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            if (d is System.Windows.Window window)
+            {
+                if ((bool)e.NewValue)
+                {
+                    window.PreviewKeyDown += Window_PreviewKeyDown;
+                }
+                else
+                {
+                    window.PreviewKeyDown -= Window_PreviewKeyDown;
+                }
+            }
+        }
+
+        private static void Window_PreviewKeyDown(object sender, KeyEventArgs e)
+        {
+            if (e.Key == Key.System && e.SystemKey == Key.F4)
+            {
+                e.Handled = true;
+            }
+        }
+
+        public static void SetIgnoreAltF4(DependencyObject element, bool value)
+            => element.SetValue(IgnoreAltF4Property, value);
+
+        public static bool GetIgnoreAltF4(DependencyObject element)
+            => (bool) element.GetValue(IgnoreAltF4Property);
     }
 }
\ No newline at end of file
diff --git a/src/Shared/HandyControl_Shared/Controls/Input/NumericUpDown.cs b/src/Shared/HandyControl_Shared/Controls/Input/NumericUpDown.cs
index f4b8aa78..761fa2d9 100644
--- a/src/Shared/HandyControl_Shared/Controls/Input/NumericUpDown.cs
+++ b/src/Shared/HandyControl_Shared/Controls/Input/NumericUpDown.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Windows;
 using System.Windows.Controls;
-using System.Windows.Documents;
 using System.Windows.Input;
 using HandyControl.Data;
 using HandyControl.Interactivity;