wpf无边框（无顶部白边）

<Window x:Class="dnh_ocr.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:dnh_ocr"
        mc:Ignorable="d"
        Title="大挪耗www.ha0wen.top" Height="398" Width="506">
    <WindowChrome.WindowChrome>
        <WindowChrome CaptionHeight="30"  GlassFrameThickness="-1" UseAeroCaptionButtons="False"/>
    </WindowChrome.WindowChrome>
    <Window.Resources>
        <Style TargetType="{x:Type Panel}" x:Key="WinRootPanelStyle">
            <Setter Property="Margin" Value="0" />
            <Style.Triggers>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type Window}}, Path=WindowState}" Value="Maximized">
                    <Setter Property="Margin" Value="7" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <Grid ShowGridLines="True" IsHitTestVisible="True" WindowChrome.IsHitTestVisibleInChrome="True" Style="{StaticResource WinRootPanelStyle}">

        <Grid.RowDefinitions>
            <RowDefinition Height="30"/>
            <RowDefinition Height="20"/>
            <RowDefinition/>
            <RowDefinition Height="20"/>
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
            <Button Height="30" Width="40" Content="—" BorderThickness="0" Click="最小化窗口"/>
            <Button Height="30" Width="40" Content="口" BorderThickness="0" Click="全屏窗口"/>
            <Button Height="30" Width="40" Content="X"  BorderThickness="0" Click="关闭窗口">
                <Button.Template>
                    <ControlTemplate TargetType="{x:Type Button}">
                        <Border x:Name="border" Height="{TemplateBinding Height}" Width="{TemplateBinding Width}" Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}">
                            <TextBlock x:Name="TextBlock" Foreground="{TemplateBinding Foreground}" Text="{TemplateBinding Content}" HorizontalAlignment="Center" VerticalAlignment="Center" />
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter TargetName="border" Property="Background" Value="#cc0000"/>
                                <Setter TargetName="TextBlock" Property="Foreground" Value="White"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Button.Template>
                
            </Button>
        </StackPanel>
        
    </Grid>
</Window>

加粗的代码是关键部分，NET8.0，另一段代码实现

using System.Text;
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 dnh_ocr
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void 关闭窗口(object sender, RoutedEventArgs e)
        {
            Close();
        }

        private void 全屏窗口(object sender, RoutedEventArgs e)
        {
           WindowMax();
        }


        private void WindowMax()
        {
            if (this.WindowState == WindowState.Normal)
            {
                this.WindowState = WindowState.Maximized;
            }
            else
            {
                this.WindowState = WindowState.Normal;
            }
        }

        private void 最小化窗口(object sender, RoutedEventArgs e)
        {
            this.WindowState = WindowState.Minimized;
        }

    }
}