这就是你的问题所在。窗口框右上方的关闭按钮不是WPF窗口的一部分，但它属于由操作系统控制的窗口框的一部分。这意味着你必须使用Win32互操作来实现。

或者，您可以使用noframe并提供您自己的“框架”或根本没有框架。

正如在其他答案中所述，您可以使用WindowStyle="None"来完全删除标题栏。

并且，正如其他答案的评论中所述，这阻止了窗口的可拖动性，因此很难将其从初始位置移动。

但是，你可以通过在窗口的代码后面文件的构造函数中添加一行代码来克服这个问题:

MouseDown += delegate { DragMove(); };

或者，如果你喜欢Lambda语法:

MouseDown += (sender, args) => DragMove();

这使得整个窗口可拖动。窗口中出现的任何交互控件，如按钮，仍将正常工作，不会作为窗口的拖拽句柄。

使用这个，从https://stephenhaunts.com/2014/09/25/remove-the-close-button-from-a-wpf-window修改:

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

namespace Whatever
{
    public partial class MainMenu : Window
    {
        private const int GWL_STYLE = -16;
        private const int WS_SYSMENU = 0x00080000;

        [DllImport("user32.dll", SetLastError = true)]
        private static extern int GetWindowLongPtr(IntPtr hWnd, int nIndex);

        [DllImport("user32.dll")]
        private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

        public MainMenu()
        {
             InitializeComponent();
             this.Loaded += new RoutedEventHandler(Window_Loaded);
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            var hwnd = new WindowInteropHelper(this).Handle;
            SetWindowLongPtr(hwnd, GWL_STYLE, GetWindowLongPtr(hwnd, GWL_STYLE) & ~WS_SYSMENU);
        }  

    }
}

You may run into the need to toggle the window state depending on what page or user control is currently being displayed. (Yes, this is an unusual scenario, but it can happen. In our case we have a user control in our application that is displayed on an external touch screen for customers to interact with. We don't want our customers to have touch access to close the screen. But the rest of the application uses standard windows frames.) To do this from the code behind of the page or user control. Note: You must run it from the Loaded event not the constructor because the control hasn't been populated in the constructor and it will throw an exception.

// To toggle it off
Window.GetWindow(this).WindowStyle = WindowStyle.None;

// To turn it back on toggle it off
Window.GetWindow(this).WindowStyle = WindowStyle.SingleBorderWindow;

在寻找了很多答案之后，我想出了这个简单的解决方法，我将在这里分享，希望它能帮助到其他人。

我设置WindowStyle=0x10000000。

这设置了窗口样式的WS_VISIBLE (0x10000000)和WS_OVERLAPPED (0x0)值。"Overlapped"是显示标题栏和窗口边框的必要值。通过从我的样式值中删除WS_MINIMIZEBOX (0x20000)、WS_MAXIMIZEBOX (0x10000)和WS_SYSMENU (0x80000)值，标题栏中的所有按钮都被删除了，包括关闭按钮。

要禁用关闭按钮，你应该添加以下代码到你的Window类(代码是从这里，编辑和重新格式化一点):

protected override void OnSourceInitialized(EventArgs e)
{
    base.OnSourceInitialized(e);

    HwndSource hwndSource = PresentationSource.FromVisual(this) as HwndSource;

    if (hwndSource != null)
    {
        hwndSource.AddHook(HwndSourceHook);
    }

}

private bool allowClosing = false;

[DllImport("user32.dll")]
private static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
[DllImport("user32.dll")]
private static extern bool EnableMenuItem(IntPtr hMenu, uint uIDEnableItem, uint uEnable);

private const uint MF_BYCOMMAND = 0x00000000;
private const uint MF_GRAYED = 0x00000001;

private const uint SC_CLOSE = 0xF060;

private const int WM_SHOWWINDOW = 0x00000018;
private const int WM_CLOSE = 0x10;

private IntPtr HwndSourceHook(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    switch (msg)
    {
        case WM_SHOWWINDOW:
            {
                IntPtr hMenu = GetSystemMenu(hwnd, false);
                if (hMenu != IntPtr.Zero)
                {
                    EnableMenuItem(hMenu, SC_CLOSE, MF_BYCOMMAND | MF_GRAYED);
                }
            }
            break;
        case WM_CLOSE:
            if (!allowClosing)
            {
                handled = true;
            }
            break;
    }
    return IntPtr.Zero;
}

这段代码还禁用了系统菜单中的关闭项，并禁止使用Alt+F4关闭对话框。

您可能希望以编程方式关闭该窗口。仅仅调用Close()是行不通的。你可以这样做:

allowClosing = true;
Close();