class DragForm
    {
        private int x;
        private int y;
        private Point yyy;
        private bool _t;
        public bool t
        {
            get { return t; }
            set { _t = value; }
        }
        public void setXy(Control f)
        {
            yyy =f.PointToClient(Control.MousePosition);
        }
        public void dragForm(Control f)
        {
            Point xxx = Control.MousePosition;
            x = xxx.X;
            y = xxx.Y;
            if (_t == true)
            {
                f.Top = y - yyy.Y;
                f.Left = x - yyy.X;
            }
        }
    }