直接上范例：

public class MaskWindow : ReuseWindow
{
    public MaskWindow() : base()
    {
        WindowStyle = System.Windows.WindowStyle.None;
        AllowsTransparency = true;
        ShowInTaskbar = false;
        ResizeMode = System.Windows.ResizeMode.NoResize;
        Title = "MaskWindow";
        Background = new SolidColorBrush(Color.FromArgb(40, 0, 0, 0));
        MouseDown += Window_MouseDown;
        KeyDown += Window_KeyDown;
    }

    private void Window_MouseDown(object sender, MouseButtonEventArgs e)
    {
        WindowManager.FocusSearch();
    }

    private void Window_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Escape)
        {
            new Thread(() =>
            {
                WindowManager.EndProcess();
            }).Start();
        }
    }
}

使用的时候：

public partial class ScreenMaskWindow : MaskWindow
{
    public ScreenMaskWindow()
    {
        InitializeComponent();
    }
}

<local:MaskWindow x:Class="Ayase.UI.ScreenMaskWindow"
        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:Ayase.UI"
        mc:Ignorable="d"
        Activated="MaskWindow_Activated"
        Title="ScreenMaskWindow" Height="450" Width="800">
    <Grid>

    </Grid>
</local:MaskWindow>

最外层标签从原来的Window改为了local:MaskWindow（即自定义的类），这里IDE会自动提示的，无需担心。