下面的文字，缺省值是在屏幕中间显示。

DialogResult dr = MessageBox.Show("是否要删除此数据？", "删除确认", MessageBoxButtons.OKCancel,MessageBoxIcon.Information,MessageBoxDefaultButton.Button2);

if (dr == DialogResult.Cancel)

{

    return;

}

要让MessageBoxEx.Show显示在父窗口中间，须要又一次写个以下的类。调用WINAPI函数。

using System;

using System.Windows.Forms;

using System.Text;

using System.Drawing;

using System.Runtime.InteropServices;

public class MessageBoxEx

{

    private static IWin32Window _owner;

    private static HookProc _hookProc;

    private static IntPtr _hHook;

    public static DialogResult Show(string text)

    {

        Initialize();

        return MessageBox.Show(text);

    }

    public static DialogResult Show(string text, string caption)

    {

        Initialize();

        return MessageBox.Show(text, caption);

    }

    public static DialogResult Show(string text, string caption, MessageBoxButtons buttons)

    {

        Initialize();

        return MessageBox.Show(text, caption, buttons);

    }

    public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon)

    {

        Initialize();

        return MessageBox.Show(text, caption, buttons, icon);

    }

    public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton)

    {

        Initialize();

        return MessageBox.Show(text, caption, buttons, icon, defButton);

    }

    public static DialogResult Show(string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton, MessageBoxOptions options)

    {

        Initialize();

        return MessageBox.Show(text, caption, buttons, icon, defButton, options);

    }

    public static DialogResult Show(IWin32Window owner, string text)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text);

    }

    public static DialogResult Show(IWin32Window owner, string text, string caption)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text, caption);

    }

    public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text, caption, buttons);

    }

    public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text, caption, buttons, icon);

    }

    public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text, caption, buttons, icon, defButton);

    }

    public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defButton, MessageBoxOptions options)

    {

        _owner = owner;

        Initialize();

        return MessageBox.Show(owner, text, caption, buttons, icon,

                               defButton, options);

    }

    public delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);

    public delegate void TimerProc(IntPtr hWnd, uint uMsg, UIntPtr nIDEvent, uint dwTime);

    public const int WH_CALLWNDPROCRET = 12;

    public enum CbtHookAction : int

    {

        HCBT_MOVESIZE = 0,

        HCBT_MINMAX = 1,

        HCBT_QS = 2,

        HCBT_CREATEWND = 3,

        HCBT_DESTROYWND = 4,

        HCBT_ACTIVATE = 5,

        HCBT_CLICKSKIPPED = 6,

        HCBT_KEYSKIPPED = 7,

        HCBT_SYSCOMMAND = 8,

        HCBT_SETFOCUS = 9

    }

    [DllImport("user32.dll")]

    private static extern bool GetWindowRect(IntPtr hWnd, ref Rectangle lpRect);

    [DllImport("user32.dll")]

    private static extern int MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

    [DllImport("User32.dll")]

    public static extern UIntPtr SetTimer(IntPtr hWnd, UIntPtr nIDEvent, uint uElapse, TimerProc lpTimerFunc);

    [DllImport("User32.dll")]

    public static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll")]

    public static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId);

    [DllImport("user32.dll")]

    public static extern int UnhookWindowsHookEx(IntPtr idHook);

    [DllImport("user32.dll")]

    public static extern IntPtr CallNextHookEx(IntPtr idHook, int nCode, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll")]

    public static extern int GetWindowTextLength(IntPtr hWnd);

    [DllImport("user32.dll")]

    public static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int maxLength);

    [DllImport("user32.dll")]

    public static extern int EndDialog(IntPtr hDlg, IntPtr nResult);

    [StructLayout(LayoutKind.Sequential)]

    public struct CWPRETSTRUCT

    {

        public IntPtr lResult;

        public IntPtr lParam;

        public IntPtr wParam;

        public uint message;

        public IntPtr hwnd;

    } ;

    static MessageBoxEx()

    {

        _hookProc = new HookProc(MessageBoxHookProc);

        _hHook = IntPtr.Zero;

    }

    private static void Initialize()

    {

        if (_hHook != IntPtr.Zero)

        {

            throw new NotSupportedException("multiple calls are not supported");

        }

        if (_owner != null)

        {

            _hHook = SetWindowsHookEx(WH_CALLWNDPROCRET, _hookProc, IntPtr.Zero, AppDomain.GetCurrentThreadId());

        }

    }

    private static IntPtr MessageBoxHookProc(int nCode, IntPtr wParam, IntPtr lParam)

    {

        if (nCode < 0)

        {

            return CallNextHookEx(_hHook, nCode, wParam, lParam);

        }

        CWPRETSTRUCT msg = (CWPRETSTRUCT)Marshal.PtrToStructure(lParam, typeof(CWPRETSTRUCT));

        IntPtr hook = _hHook;

        if (msg.message == (int)CbtHookAction.HCBT_ACTIVATE)

        {

            try

            {

                CenterWindow(msg.hwnd);

            }

            finally

            {

                UnhookWindowsHookEx(_hHook);

                _hHook = IntPtr.Zero;

            }

        }

        return CallNextHookEx(hook, nCode, wParam, lParam);

    }

    private static void CenterWindow(IntPtr hChildWnd)

    {

        Rectangle recChild = new Rectangle(0, 0, 0, 0);

        bool success = GetWindowRect(hChildWnd, ref recChild);

        int width = recChild.Width - recChild.X;

        int height = recChild.Height - recChild.Y;

        Rectangle recParent = new Rectangle(0, 0, 0, 0);

        success = GetWindowRect(_owner.Handle, ref recParent);

        Point ptCenter = new Point(0, 0);

        ptCenter.X = recParent.X + ((recParent.Width - recParent.X) / 2);

        ptCenter.Y = recParent.Y + ((recParent.Height - recParent.Y) / 2);

        Point ptStart = new Point(0, 0);

        ptStart.X = (ptCenter.X - (width / 2));

        ptStart.Y = (ptCenter.Y - (height / 2));

        ptStart.X = (ptStart.X < 0) ? 0 : ptStart.X;

        ptStart.Y = (ptStart.Y < 0) ? 0 : ptStart.Y;

        int result = MoveWindow(hChildWnd, ptStart.X, ptStart.Y, width, height, false);

    }

}

调用方式

DialogResult dr = MessageBoxEx.Show(this,"是否要删除此数据？", "删除确认", MessageBoxButtons.OKCancel, MessageBoxIcon.Information, MessageBoxDefaultButton.Button2);

if (dr == DialogResult.Cancel)

{

    return;

}