我现在有个from窗体，设置了最大和最小尺寸，现在运行时，是显示在中间，最大化后，跑到了左上角，我现在想拖动这个窗体，保持最大化的状态不变，怎么实现呢，谢谢大牛们

处理窗体消息，如下：

using System.Drawing;
using System.Windows.Forms;

namespace DragWindowWithMaxSize
{
    public sealed partial class FormMain : Form
    {
        #region 常量

        private const int WM_NCLBUTTONDBLCLK = 0x00a3;
        private const int WM_SYSCOMMAND      = 0x0112;
        private const int SC_MAXMIZE         = 0xf030;

        #endregion

        public FormMain()
        {
            InitializeComponent();
        }

        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                case WM_NCLBUTTONDBLCLK:
                    {
                        if (WindowState == FormWindowState.Normal)
                        {
                            Location = new Point(0,0);
                            Size = MaximumSize;
                        }
                    }
                    break;

                case WM_SYSCOMMAND:
                    {
                        switch((uint)m.WParam)
                        {
                            case SC_MAXMIZE:
                                Size = MaximumSize;
                                WindowState = FormWindowState.Maximized;
                                return;
                        }
                    }
                    break;
            }
            base.WndProc(ref m);
           
        }
    }
}

[ 本帖最后由 mmxo 于 2012-11-22 18:52 编辑 ]

        #region 本程序中用到的API函数
        [DllImport("user32.dll")]
        public static extern bool ReleaseCapture();//用来释放被当前线程中某个窗口捕获的光标
        [DllImport("user32.dll")]
        public static extern bool SendMessage(IntPtr hwdn, int wMsg, int mParam, int lParam);//向指定的窗体发送Windows消息
        #endregion

        #region 本程序中需要声明的变量
        public const int WM_SYSCOMMAND = 0x0112;//该变量表示将向Windows发送的消息类型
        public const int SC_MOVE = 0xF010;//该变量表示发送消息的附加消息
        public const int HTCAPTION = 0x0002;//该变量表示发送消息的附加消息
        #endregion

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            ReleaseCapture();//用来释放被当前线程中某个窗口捕获的光标
            SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0);//向Windows发送拖动窗体的消息
        }

Form1.Designer.cs

//
// Form1
//
加入：
this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.Form1_MouseDown);

非常感谢

改窗体属性页可以，免去输代码