/// <summary>
            /// Handles the Tick event of the timer control.
            /// </summary>
            /// <param name="sender">The source of the event.</param>
            /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
            private void timer_Tick(object sender, EventArgs e)
            {
                Timer         timer   = (Timer)sender;
                AnimateMsgBox animate = (AnimateMsgBox)timer.Tag;

                if (DropDownForm.Height < animate.FormSize.Height)
                {
                    DropDownForm.Height += animate.FormSize.Height / 20;
                    if (DropDownForm.Height > animate.FormSize.Height)
                    {
                        DropDownForm.Height = animate.FormSize.Height;
                    }
                    DropDownForm.Invalidate();
                }
                else
                {
                    _timer.Stop();
                    _timer.Dispose();
                }
            }