我的借口
请原谅我对Stackoverflow缺乏经验，但我想我会尝试帮助你一点。
我没有编写这段代码，但是看到这段代码对大多数人来说是不容易获得的，这里是：

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;

namespace BlurBehindDemo
{
internal enum AccentState
{
    ACCENT_DISABLED = 1,
    ACCENT_ENABLE_GRADIENT = 0,
    ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
    ACCENT_ENABLE_BLURBEHIND = 3,
    ACCENT_INVALID_STATE = 4
}

[StructLayout(LayoutKind.Sequential)]
internal struct AccentPolicy
{
    public AccentState AccentState;
    public int AccentFlags;
    public int GradientColor;
    public int AnimationId;
}

[StructLayout(LayoutKind.Sequential)]
internal struct WindowCompositionAttributeData
{
    public WindowCompositionAttribute Attribute;
    public IntPtr Data;
    public int SizeOfData;
}

internal enum WindowCompositionAttribute
{
    // ...
    WCA_ACCENT_POLICY = 19
    // ...
}

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    [DllImport("user32.dll")]
    internal static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        EnableBlur();
    }

    internal void EnableBlur()
    {
        var windowHelper = new WindowInteropHelper(this);

        var accent = new AccentPolicy();
        accent.AccentState = AccentState.ACCENT_ENABLE_BLURBEHIND;

        var accentStructSize = Marshal.SizeOf(accent);

        var accentPtr = Marshal.AllocHGlobal(accentStructSize);
        Marshal.StructureToPtr(accent, accentPtr, false);

        var data = new WindowCompositionAttributeData();
        data.Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY;
        data.SizeOfData = accentStructSize;
        data.Data = accentPtr;

        SetWindowCompositionAttribute(windowHelper.Handle, ref data);

        Marshal.FreeHGlobal(accentPtr);
    }

    private void Window_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        DragMove();
    }
}

}

结果

一旦实施，这将影响整个窗口，如图所示：

经过一点调整

XAML

这是我几个月前做的一个项目，所以它看起来和你的不一样，但是经过一些调整，你可以很容易地把它变成你想要的任何东西。我设计的XAML如下：

<Window
    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" mc:Ignorable="d" x:Class="MainWindow"
    Title="Blurred Opacity" Height="623" Width="752"
    Background="#727A7A7A"
    AllowsTransparency="True"
    WindowStyle="None"
    BorderThickness="1"
    WindowStartupLocation="CenterScreen"
    Loaded="Window_Loaded" MouseLeftButtonDown="Window_MouseDown" Topmost="True" BorderBrush="#FF1E9EC5">
<Grid>
    <Rectangle Fill="#FF0143A4" Height="130" VerticalAlignment="Top"/>
    <Rectangle Fill="White" Margin="0,130,0,0" HorizontalAlignment="Right" Width="375"/>
    <StackPanel HorizontalAlignment="Left" Margin="0,130,0,0" Width="375">
        <TextBlock x:Name="textBlock" Height="50" TextWrapping="Wrap" Text="Category 1" d:LayoutOverrides="LeftPosition, RightPosition" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6"/>
        <TextBlock x:Name="textBlock_Copy" Height="50" TextWrapping="Wrap" Text="Category 2" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy1" Height="50" TextWrapping="Wrap" Text="Category 3" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy2" Height="50" TextWrapping="Wrap" Text="Category 4" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy3" Height="50" TextWrapping="Wrap" Text="Category 5" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy4" Height="50" TextWrapping="Wrap" Text="Category 6" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy5" Height="50" TextWrapping="Wrap" Text="Category 7" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy6" Height="50" TextWrapping="Wrap" Text="Category 8" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
    </StackPanel>
    <TextBlock x:Name="textBlock_Copy7" Height="90" TextWrapping="Wrap" Text="Example" FontSize="65" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" Margin="222.5,23,152.5,0" VerticalAlignment="Top" Foreground="White"/>
    <Path Data="M705,27.333333 L735.66667,10" Fill="White" HorizontalAlignment="Right" Height="24" Margin="0,7,21,0" Stretch="Fill" VerticalAlignment="Top" Width="24" StrokeThickness="3" Stroke="White"/>
    <Path Data="M705,27.333333 L735.66667,10" Fill="White" HorizontalAlignment="Right" Height="24.083" Margin="0,6.833,20.333,0" Stretch="Fill" VerticalAlignment="Top" Width="24.167" StrokeThickness="3" Stroke="White" RenderTransformOrigin="0.5,0.5">
        <Path.RenderTransform>
            <TransformGroup>
                <ScaleTransform ScaleX="-1"/>
                <SkewTransform/>
                <RotateTransform/>
                <TranslateTransform/>
            </TransformGroup>
        </Path.RenderTransform>
    </Path>
    <StackPanel HorizontalAlignment="Right" Margin="0,130,0,0" Width="375">
        <TextBlock x:Name="textBlock1" Height="50" TextWrapping="Wrap" Text="Item 1" d:LayoutOverrides="LeftPosition, RightPosition" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6"/>
        <TextBlock x:Name="textBlock_Copy8" Height="50" TextWrapping="Wrap" Text="Item 2" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"/>
        <TextBlock x:Name="textBlock_Copy9" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="3"/><LineBreak/><Run Text="3"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy10" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="4"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy11" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="5"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy12" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="6"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy13" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="7"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy14" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="8"/></TextBlock>
        <TextBlock x:Name="textBlock_Copy15" Height="50" TextWrapping="Wrap" FontSize="35" Padding="10,0,0,0" TextOptions.TextFormattingMode="Display" LineHeight="6" d:LayoutOverrides="LeftPosition, RightPosition"><Run Text="Item "/><Run Text="9"/></TextBlock>
    </StackPanel>
</Grid>

希望这对你有帮助！

您可以使用网格中的项目位于其他项目之上的事实：

<Grid >
    <Image Source="texture-7.jpg" Stretch="Fill" >
        <Image.Effect>
            <BlurEffect Radius="100"/>
        </Image.Effect>
    </Image>
    <Canvas Background="Transparent">
        <!-- Content -->
    </Canvas>
</Grid>

其中“texture-7.jpg”是纹理的某个图像。如果你还想让它透明，只需设置Image的opacity属性

使用Windows10时，请查看BlurryControls。它提供了一个你可以直接继承的模糊窗口。
对于Windows8没有解决方案模糊一个窗口（据我所知）。
对于Windows7/Vista，一个名为Ciantic的用户提供了以下解决方案：Windows Aero Glass.工作样品溶液可在此处找到：GlassingExtension。
我希望这能回答你的问题。如果您对针对Windows 10的解决方案有问题或建议，请回复。

希望这有帮助

<Canvas  Height="300" Width="300">
    <Canvas.Background>
        <VisualBrush Stretch="None">
            <VisualBrush.Visual>
                <Canvas Background="LightBlue" Height="300" Width="300">
                    <Canvas.Effect>
                        <BlurEffect Radius="150"></BlurEffect>
                    </Canvas.Effect>
                </Canvas>
            </VisualBrush.Visual>
        </VisualBrush>
    </Canvas.Background>
    <Rectangle Fill="Red" Height="50" Width="50"></Rectangle>
    <Rectangle Fill="Green" Margin="50" Height="50" Width="50"></Rectangle>
</Canvas>