public frm_Main()
        {
            InitializeComponent();

            //button21.Visible = false;
            //button41.Visible = false;

            hinhTru                   = new HinhTru(10, -10, 0, 30, 10);
            hinhTruProperties         = new HinhTruProperties();
            hinhTruProperties.Visible = false;

            hinhHopChuNhat                   = new HinhHopChuNhat(0, 0, 0, 10, 10, 10);
            hinhHopChuNhatProperties         = new HinhHopChuNhatProperties();
            hinhHopChuNhatProperties.Visible = false;

            // Tạo quả lắc theo kích thước cho trước
            pendulum = new Pendulum(new Point(100, 20), new Point(400, 220));
            pendulum.SetAlpha(-3); // set góc quay alpha
            pendulum.PropertyChanged += Pendulum_PropertyChanged;

            //2D mode is startup;
            Setup_Toolbar(Globals._Mode_current);
            picb_2DArea.Dock = picb_3DArea.Dock = DockStyle.Fill;

            Setup_ToolTips();
            flagXe = false;
        }
        private void HinhTruProperties_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            string[] str        = e.PropertyName.Split(',');
            int      x          = Int16.Parse(str[0]),
                     y          = Int16.Parse(str[1]),
                     z          = Int16.Parse(str[2]),
                     chieuCao   = Int16.Parse(str[3]),
                     banKinhDay = Int16.Parse(str[4]);

            hinhTru = new HinhTru(x, y, z, chieuCao, banKinhDay);

            picb_3DArea.Refresh();
            hinhTru.Draw(picb_3DArea.CreateGraphics());
        }