C# と VB.NET の質問掲示板

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ソースを載せさせて頂きますので、よろしくお願いいたします。
    class ControlMoveHelper
    {

        private Control control;

        private bool isDragged = false;

        private bool doAction = true;

        public bool DoAction
        {
            set { this.doAction = value; }
            get { return this.doAction; }
        }

        private Point point = new Point();

        private int margin;

        public ControlMoveHelper(Control control,  int margin)
             : this(control,  null, margin){}

        public ControlMoveHelper(Control control, Control[] eventControls, int margin)
        {
            this.control = control;
            this.margin = margin;

            this.control.MouseDown += new MouseEventHandler(control_MouseDown);
            this.control.MouseUp += new MouseEventHandler(control_MouseUp);
            this.control.MouseMove += new MouseEventHandler(control_MouseMove);

            if (eventControls != null)
            {
                foreach (Control eventControl in eventControls)
                {
                    eventControl.MouseDown += new MouseEventHandler(control_MouseDown);
                    eventControl.MouseUp += new MouseEventHandler(control_MouseUp);
                    eventControl.MouseMove += new MouseEventHandler(control_MouseMove);
                }
            }
        }

        /// <summary>
        /// マウスが動かされた場合の処理
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void control_MouseMove(object sender, MouseEventArgs e)
        {
            if (!this.doAction) { return; }

            if (this.isDragged)
            {
                //Point point = this.control.PointToScreen(new Point(e.X, e.Y));
                Point point = ((Control)sender).PointToScreen(new Point(e.X, e.Y));
                this.control.Top += point.Y - this.point.Y;
                this.control.Left += point.X - this.point.X;
                //this.control.Top += e.Y - this.point.Y;
                //this.control.Left += e.X - this.point.X;
            }
            else
            {
                if (this.IsRange(e))
                {
                    this.control.Cursor = Cursors.SizeAll;
                }
            }
        }

        /// <summary>
        /// マウスがアップした場合の処理
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void control_MouseUp(object sender, MouseEventArgs e)
        {
            if (!this.doAction) { return; }

            this.isDragged = false;
        }

        /// <summary>
        /// マウスがダウンされた場合の処理
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void control_MouseDown(object sender, MouseEventArgs e)
        {
            if (!this.doAction) { return; }

            if (this.IsRange(e))
            {
                //this.point.X = e.X;
                //this.point.Y = e.Y;
                //this.point = this.control.PointToScreen(new Point(e.X, e.Y));
                this.point = ((Control)sender).PointToScreen(new Point(e.X, e.Y));

                this.isDragged = true;
            }
        }

        private bool IsRange(MouseEventArgs e)
        {
            Rectangle range = new Rectangle(this.margin, this.margin, this.control.Width - this.margin * 2, this.control.Height - this.margin * 2);
    
            return range.Contains(e.Location);
        }
    }