wpf 无边框窗体

<Window x:Class="UserControlDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:UserControlDemo"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" WindowStyle="None"
        WindowChrome.WindowChrome="{DynamicResource WindowChromeKey}"  Background="#1BA1E2" >
    <Window.Resources>
        <WindowChrome x:Key="WindowChromeKey">
            <WindowChrome.ResizeBorderThickness>
                <Thickness>5</Thickness>
            </WindowChrome.ResizeBorderThickness>
        </WindowChrome>
    </Window.Resources>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="50"></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Label Content="Main Window" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="White" FontSize="30"></Label>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right"  VerticalAlignment="Top">
            <Button x:Name="btnMinimize" Height="20" Width="20" Content="-"  Click="BtnMinimize_Click"/>
            <Button x:Name="btnMaximize" Height="20" Width="20" Content="□" Click="BtnMaximize_Click"/>
            <Button x:Name="btnClose" Height="20" Width="20" Content="×" Click="BtnClose_Click"/>
        </StackPanel>
    </Grid>


</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace UserControlDemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {           
            InitializeComponent();
        }

        private void BtnMinimize_Click(object sender, RoutedEventArgs e)
        {
            this.WindowState = WindowState.Minimized;
        }

        private void BtnMaximize_Click(object sender, RoutedEventArgs e)
        {
            this.WindowState = WindowState.Maximized;
        }

        private void BtnClose_Click(object sender, RoutedEventArgs e)
        {
            this.Close();
        }
    }

  
}