//在窗体放置一个按钮  button1

         private bool isMouseDown = false;  //记录按钮是否被按下

        private Point mouseOffset;              //记录鼠标指针的坐标

        public Form1()

        {

            InitializeComponent();

            this.button1.MouseMove += new MouseEventHandler(button1_MouseMove);

            this.button1.MouseDown += new MouseEventHandler(button1_MouseDown);

            this.button1.MouseUp += new MouseEventHandler(button1_MouseUp);

        }

        void button1_MouseUp(object sender, MouseEventArgs e)

        {

            if (e.Button == MouseButtons.Left)

            {

                isMouseDown = false;     //如果左边按钮弹起

            }

        }

        void button1_MouseDown(object sender, MouseEventArgs e)

        {

            if (e.Button == MouseButtons.Left)

            {

                mouseOffset.X = e.X;

                mouseOffset.Y = e.Y;

                isMouseDown = true;

            }

        

        }

        void button1_MouseMove(object sender, MouseEventArgs e)

        {

            if (isMouseDown)

            {

                int left = button1.Left + e.X - mouseOffset.X;

                int top = button1.Top + e.Y - mouseOffset.Y;

                button1.Location = new Point(left, top);

            }

        }