1. 启动程序,图如下:

 

2. 拖动 Button 后的效果如下:

 

 

3. 程序源代码如下:

public partial class TestControlDrag : Form    {        /// 
        /// 该指标指示被拖动的对象是否进入了控件的边界         /// 
        bool bMouseDown;        public TestControlDrag()        {            InitializeComponent();            // 默认为 false,即不接受用户拖动到其上的控件              this.groupBox1.AllowDrop = true;            this.groupBox2.AllowDrop = true;            // 拖动对象进入控件边界时触发              this.groupBox1.DragEnter += new DragEventHandler(groupBox_DragEnter);            this.groupBox2.DragEnter += new DragEventHandler(groupBox_DragEnter);            // 完成拖动时触发              this.groupBox1.DragDrop += new DragEventHandler(groupBox_DragDrop);            this.groupBox2.DragDrop += new DragEventHandler(groupBox_DragDrop);        }        private void TestControlDrag_Load(object sender, EventArgs e)        {            CreateControls();        }        /// 
        /// 生成一定数量的控件,本例中使用 Button        /// 注册 Button 的鼠标点击事件         /// 
        private void CreateControls()        {            int x = 15;            int y = 15;            Button btn = null;            for (int i = 1; i <= 15; i++)            {                btn = new Button();                btn.Left = x;                btn.Top = y;                btn.Text = "Button " + i;                btn.Width = 100;                btn.Height = 50;                x += btn.Width + 15;                if (btn.Width > groupBox1.Width - x)                {                    x = 15;                    y += btn.Height + 15;                }                btn.AllowDrop = true; // 默认为 false,即不可拖动                   btn.MouseDown += new MouseEventHandler(btn_MouseDown);                this.groupBox1.Controls.Add(btn);            }        }        /// 
        /// 拖动对象进入本控件的边界         /// 
        void groupBox_DragEnter(object sender, DragEventArgs e)        {            e.Effect = DragDropEffects.Move;            bMouseDown = true;        }        /// 
        /// 拖放操作完成         /// 
        void groupBox_DragDrop(object sender, DragEventArgs e)        {            if (bMouseDown)            {                // 从事件参数 DragEventArgs 中获取被拖动的元素                   Button btn = (Button)e.Data.GetData(typeof(Button));                GroupBox grp = (GroupBox)btn.Parent;                grp.Controls.Remove(btn);                ((GroupBox)sender).Controls.Add(btn);                RefreshControls(new Control[] { grp, (GroupBox)sender });                bMouseDown = false;            }        }        /// 
        /// 按下鼠标后即开始执行拖放操作         /// 这里指定了拖放操作的最终效果为一个枚举值: Move        /// 
        void btn_MouseDown(object sender, MouseEventArgs e)        {            Button btn = (Button)sender;            btn.DoDragDrop(btn, DragDropEffects.Move);        }        /// 
        /// 对控件中的项进行排列         /// 
        private void RefreshControls(Control[] p)        {            foreach (Control control in p)            {                int x = 15;                int y = 15;                Button btn = null;                foreach (Control var in control.Controls)                {                    btn = var as Button;                    btn.Left = x;                    btn.Top = y;                    x += btn.Width + 15;                    if (btn.Width > control.Width - x)                    {                        x = 15;                        y += btn.Height + 15;                    }                }            }        }    }