if (e.Button == MouseButtons.Left)
        {
          //
        }
        if (e.Button == MouseButtons.Right)
        {
          //
        }

 switch (MouseButtons)
            {
                case System.Windows.Forms.MouseButtons.Left:
                  //
                    break;
                case System.Windows.Forms.MouseButtons.Right:
                   //
                    break;
                case System.Windows.Forms.MouseButtons.Middle:
                   //
                    break;
            }